SS isn't harming your marriage, your husband is.  No, you are not overreacting.  I'd find a new therapist.  If your husband throws you under the bus, no, you shouldn't be ok within yourself.  What kind of nonsense is that?  Your husband is supposed to put you first and protect you, even if it is from his jerk of a son.  His son didn't respect your boundaries, neither did your husband.  Then he pretty much ignored you for a month.  

And who the h3!! does SS think he is telling his dad to exclude you from family functions?  That is not up to him, especially if he is not the one hosting them.  I hope he isn't going to be staying in your home.  I would be putting my foot down on that and if my husband didn't like it I'd put my foot so far up his behind his breath would smell like shoe polish.  

My SS was never openly rude to me.  He even claimed that he considered me his mother.  He didn't treat me like he felt that way though.  He treated me like I was just dad's wife, or girlfriend.  I helped raise him, the little lying ingrate!  Sure, he was polite.  But while he was spewing his BS, and claiming he wanted me to be a grandma to his spawn, he was excluding me from even getting pictures.  He only texted my husband.  Like how hard is it to group text if you want to include somebody?  We both called him out on his crap but he just continued lying, pulling nonsense out of thin air, even claiming that I made no effort to have a relationship with him.  Which was a lie and I had the texts that I sent him as proof that I in fact did make an effort to keep in touch.  Know what my husband did?  He quit talking to him.  He wasn't going to stand for someone treating his wife like that. The wife who helped raise his son, who was there when BM wasn't.  Had I not raised him it would be more understandable for us to just be polite in-laws or something.  It wasn't just the text messages, that was only an example of what I was talking about.  

If you can stomach being in the same room with him, then go to family functions where he'll be and just ignore him.  He shouldn't be allowed in your home though.  That's your domain, your sanctuary.  Your husband can see him outside of your home.  Me, personally, I refused to go around mine.  I also felt as if my husband was sending the message that he was ok with how SS and his awful wife acted if he kept going around them so didn't want my bios going around them either.  I couldn't have stopped my husband.  He chose on his own to stop talking to him.  I'm sure it hurt.  My life is more peaceful without SS and his wife in it.  The thought of being around them gave me anxiety and high blood pressure.  Who needs that?

There is no way that anyone could not let it "erode their love for their husband" - as you yourself put it, your husband was willing to treat you like caca on orders from his son - which is utterly ludicrous.  Ordering you home from Egypt and refusing to speak to you on the phone?  I do NOT agree with your therapist - and I myself used to be a relationship counsellor.  I would look, rather, at why your childhood influences induce you to put up with abusive treatment from your life partner.  You mention the possibility of divorce several times in your post.  I think you should be making serious plans along these lines and certainly get your ducks in a line with regard to finance etc. 

Frankly, I would have been gone when my DuH got back from Egypt. How DARE he sent you home! 

I am so sorry your SS AND your husband are both POS's. Two years ago on your trip to Egypt, your husband showed his true colors, he is a ball - less wonder. If my DH sent me home, after asking me to go with him, I would have went home and cleaned out every bank account. Packed his sh*t and put it in the garage, change all the locks and headed to the attorney to file for divorce. In a relationship, love is only apart of it, there is trust, respect, understanding, caring and so much more.

Your husband broke your trust, showed you no respect, and cowed down to his man-baby son about understanding and caring about your safety concerns on the trip. All of these would have 100% killed any love in the relationship. Find another therapist, the one you have now is a complete idiot. After two years and the possibility of the man-baby coming to visit your resentment is probably growing quickly.

As Kes said, get your ducks in a row, open a separate secret bank account and start putting money away asap. Gather any and all important paperwork, make copies and secure them somewhere away from your home, get a security deposit box at a bank, but not at the same bank as any account that your husband has. Look out for YOUR best interest, because you husband has not and probably will not ever.

Having experienced my SO throwing me under the bus to appease his spawn. I can tell you that I absolutely harbor hurt, anger and resentment towards him for it.

Even though he has apologized, and admitted to his behavior. It doesn't change how I feel because he lost my trust. He has placed a wedge between us that I don't know will ever be fixed. Because he hurt me in a desperate attempt to salvage a relationship with someone who didn't deserve it. His behavior was inexcusable.  He showed me he was willing to step on me the person who was there for him. To chase after the person who only wants a relationship with him at Thier convenience and only if it benefits them.

If SO and I stay together. If he ever starts talking to OSD again, I can tell you I will never agree to be in the same room as her. If he ever puts her before me again, it will be the end of our relationship.

Is it really possible to distance myself from all this SS drama? How? And how to not let it erode my love for my husband?

I think your love for your DH was eroded 2 years ago when this horrific incident happened. Being passive will get you no where with your DH. This idiot really threw you under the bus, and you still desire to be with him? Your SS and your DH are both toxic. 

What real man would send his wife home from a foreign country alone because of his pathetic son's request? If I were in your shoes, DH would have either boarded that plane with me or once he returned home I would have been gone. 

You really have to value yourself and figure out why you would stay in a relationship with a man like this. What you have here is a DH who doesn't see your worth and isn't afraid to lose you while he chases this fantasy of having a healthy father son relationship with his adult son. 

If you don't stand up for yourself, who will? Don't be a doormat for these losers.  I heard someone say something like if you are a quality woman with an unworthy man, once the relationship ends his karma will be that he looks for you in every other woman he meets...which of course he never finds. Teach your DH how to treat you, or let him face his karma.

Your DH made it quite clear 2 years ago & again with catering to SS nonsense for the new trip coming. Your fears are justified. You still have the tire tracks on your back from the last go round. Somethings are unforgiveable & deal breakers. A ball-less man who has made it clear I come in second to his son would definitely be one for me. Perhaps you ought to ask yourself why it isn't for you. 

You are a marital unit. What your dh did was unforgivable. Sent you away at the request of his son?? WTH.

I can't believe your DH is allowing this. He needs to shut his son down every time he tries to exclude you or scapegoat you. What are his reasons, I'm curious? And why is their relationship back "on" as it were? What happened in those years he didn't have much contact w DH?

A couple idle thoughts:

1. your SS is not harming your marriage, your husband is. 

2. your SS is trying to control your husband. He makes demands, Daddy obeys? And you, his wife get thrown away? No. Just no. It's time for your husband to get a come to Jesus. You inform him, not ask, that you will not be treated like that by him or his son. You will not be told to take your place behind his son simply because his ADULT son wants to control your and your husband. If this is the route Dad wants, he can add divorced to the list of life accomplishments. You are not someone to be banished, you matter. What's next? Son decides to move to your home and dad kicks you out? 

I'm actually angry for you right now. The easiest word to say is "no" "No I will not cater to SS's demands." "No, I will not be treated like dirt" "No I will not be treated like dirt by you husband" "No more"

I asked hubby to check with SS and see if maybe, after 2 years, he was ready to at least see me at a family function... or were they still operating under the agreement that I was to be kept out of their relationship.

There was no reason to "check" with SS on whether or not you could attend a family function. Your SS does not control family functions and has no right to say that you cannot attend. If he cannot be a civil adult at a family function, then perhaps he should not attend.

You don't have to be part of "their relationship" but for him to dictate where you can and cannot go? Seriously, what balls.

Ughhh....I would have left the ball less git immediately after Cairo. 

What's happening here is that your weak conflict avoidant husband is letting his arrogant misogynistic son call all the shots and dictate your lives.

Your H well and truly threw you under the bus. There is NO excuse for that awful behavior, none at all.

Tell me, what do his extended family think about this situation?

Your situation sounds similar, albeit worse, than mine. I decided to stick it out, and it took years to resolve. I suffered first one thing, then another, while my DH untangled himself from his son. It's was almost funny how many ways those two invented to keep me as the third leg of their triangle.  Boundary violations, insults both subtle and open, financial stupidity--it was like a years-long game of whack-a-mole. 

I think in deciding what to do you need to assess how much --how much creativity and energy--you are willing to put into this kind of battle. If you finally win, will it have been worth it in the end? It was for me, although it destroyed a lot of the affection and respect I once felt for DH. I do wonder, though, how much respect and affection are left even in the best of circumstances after two decades of a second marriage.

This struggle is not for sissies, and money doesn't hurt. I came into the marriage with significantly more assets than DH. I have spent a chunk of money to legally protect myself from SS if DH dies before I do. Do you have financial resources? How about emotional resources? Are you capable of laying down the law and imposing your will all at once? Can you spend years fighting one battle after another?

Your DH is a fool. Good luck deciding how to deal with him.

I'm wondering if you can tell me why all that work and pain was worth it in the end. Sounds like you're still experiencing a loss of respect and affection even though you worked through a lot of the pain. So what's the "worth it part"?

Was it worth it? Yes, overall. I'm not exactly tripping over rainbows and unicorns, and many days I'm short of respect and affection for DH. But neither is my life the war zone some here endure. SS is mostly out of my hair--he doesn't hit us up for money, and he lives a miserable, hours-long drive from us, so we don't see him often. I don't doubt that DH "adores" his son (his words) but he manages to keep his offspring worship down to a dull roar. We have a working partnership, we don't fight and argue, we have good times. Overall I consider our relationship a  net positive. But I waltzed into this situation unaware of the pitfalls and blind to the red flags waving all around me. I was lucky to come out as well as I did. I probably would not try it again, and think that for most people it is a spectacularly bad move to go into a relationship with someone who has kids.

I'm also wondering if you can explain the financial risk. DH and I are more or less even on the money thing. We are comfortable and have what feels like plenty of money, although we also don't have expensive tastes or habits. DH stands to inherit a bit of money from his mother. I assume SS will see that as money that should pass to him, although as far as I know, SS has never discussed this with his dad. Certainly DH hasn't discussed it with me. DH has a will that leaves all his assets to me, his wife. Won't that protect me legally even if SS pitches a fit????

You need legal advice. Please please please talk to a lawyer--the best you can afford, someone YOU choose. See him alone and pay him out of your own pocket so that it's clear he's advocating for YOU and not some ungodly combination of your DH, his mother, and your SS. There are many stories on this site of women whose beloveds knowingly screwed them over, or died and left things in such a way that the kids were finally able to put the knife into the evil stepmother. I'm thinking of one story in particular where step son forced dad's wife out of the house she'd shared for years with her DH. That struck a chord with me. I'm legally set up so that that particular nightmare is not in my future, but the details and specifics would be useless to you. Your needs are going to be different based on your situation and the legal jurisdiction where you live. Based on what you said, you absolutely need an attorney to figure out the specifics for you. Do not trust your future to the tender mercies of your SS or, dare I say it, your DH.

As to the emotional resources question, I could certainly muster strength to fight an ongoing battle I though was worth fighting, but fighting with DH about SS is probably not something I'm willing to do long-term.

And what does "laying down the law and imposing your will all at once" look like?

I mean setting boundaries, all at once, right now, and being very clear to yourself and your DH that you will walk and stay walked at the first violation. This is another area that is specific to you and your situation, and it's not easy to figure out, let alone implement. Read around this site to get some ideas. I didn't know in advance what I would have to contend with, and ended up fighting a series of messy ground battles over a period of years. That tack is not for everyone.

I assume you would think I'm nuts to think this is going to resolve, right?

Bingo.

I guess I need to take a good hard look at reality and make some decisions . . .

Got it in one.