Sounds like the little douche didn't fall far from the douchey tree. 

You have a DH Problem. Plain and simple. 

Your husband not on!y let his kid leave the room with his teeth still intact and no bar of soap in his mouth, but he took up for the foul mouthed little brat.  Maybe if he spent more time parenting his precious poopsie instead of parenting you, his kid might be better behaved.  You got a husband problem. If he can't do any better than that, all I can say is you deserve better.  

He'd receive papers from me.

In what world would that behaviour be considered right?  Of course you were not wrong, but your DH and SS were way out of line and extraordinarily rude.  That type of behaviour deserves major consequences and should not be tolerated from your SS and especially your DH. Verbal abuse and gaslighting are not effective strategies for building a relationship or solving problems.

Considering how your husband responded, the stepson's behavior isn't surprising.  Your husband was rude and disrespectful to you - I'm sure the skid has been watching and learning for years.  You have a husband problem.  You did nothing wrong. 

Been there, done that. At one pt one of the SS was living with us and disrespectful, if i responded to his disrespect, he would record my response on his phone to show his mom (thank god i never said anything bad, just asking to not cuss or be respectful) and his dad would always try to make up excuses for his behaviors. In the end when he saw he couldnt get what he wanted, he tried to record me while i was having an argument with my husband and got in my face...it ended with assault.

Your days are numbered....In my experience, it starts with verbal abuse, then it moves on to the next.

My advice: let him cuss out his dad and one day his dad will snap and they will get in a fight. Make sure you arent there so you dont become collateral

Like this and then further gaslights the wife simply has no respect for their partner.

if you love, cherish and respect your partner, there would be hell from your husband on their kid. In fact my husband refused to allow ss to come  home from university many years ago because of all the crap behaviour of ss that hubby let slide and he wanted a break to grow a pair of balls and lay down the law, which he did.

allowing your partner talk like this to you is unacceptable 

In order for children to be raised properly to productive adults, they need a United Front which USED to be AUTOMATIC provided by mom and dad.  Both parents were at the helm guiding the "family ship."   Children did NOT have Adult Spousal Status except in very rare cases where one parent would unduly dote on the child(ren) and treat then as surrogate partners (mini spouses).

The United Front where both parents were 95% on the same page as regards child rearing was dealt a severe blow when divorce escalated.

The United Front, which is essential for well adjusted children is no longer the norm with parents taking their child's side over the other parent, SP,  school system, various cultural establishments including law enforcement, etc.

Your H is a failed parent by trying to be his offspring's best buddy and now the chickens have come home to roost.  You are just a convenient scapegoat.

Sadly, as the only adult in the room, all parties involved will view you as an interloper, despising you for it.   This cake is well past baked so the best thing you can do is admit getting involved with this trainwreck was a faux pas, that you are not responsible for any of it and RUN before it turns physical.

So this wasn't the first time? How long have you been married? 

I suggest you have a read of reedle's posts. You seem to have a lot in common. She left her toxic situation and is so much happier now. 

In no way ypur fault. Any parent that would allow that behaviour is out to lunch.  To then blame you is completely unacceptable.

Your partner, from this exchange, is abusive towards you and is allowing his toxic spawn to be abusive towards you.

This goes way beyond if you are right or wrong in this instance.

You are NOT in the wrong, except you did not follow up to SS and your DH with the following:

"Get the Fuck out of my house SS, I will not be spoken to like that!"

"DH, if you don't like it- JOIN HIM! I will not be disrespected in my home by either of you asshats."

I have lived in your world.  While my ex-SS (21) was not outwardly hostile, he was still quietly hostile and very passive aggressive, jealous of any shred of time his daddeeee spent with me.  He was entitled, lazy, and a slob - refused to work and then when he finally got a job (after 18 months of no job), he bitched because it was 10 hours/week, flunked out of online college x 2, etc, won't do his own laundry or dishes, daddeee had to make his plate and bring it to him at the table.  Gross.  And his daddeee enabled and coddled his son's behavior all the way.  While my marriage to my ex-husband was riddled with emotional and, towards the end, physical abuse, my ex-SS's behavior was also a factor in my leaving.  My ex and his manchild were blatantly rude to me, like ignoring my presence when I came home from work, locking the back door when they knew I was coming home from work and always came in that way, badmouthing me when they thought I couldn't hear, rolling their eyes at me when I came into the room or tried to join in conversation with them, doing things that excluded me.... the list goes on.  Right before I left my husband, his son was pouting because he wanted to go outside and play (remember, this is a grown man, 21 yo) and I didn't want to.  So his daddeee came in my room where I was basically hiding (I was exhausted from working all day and had no interest in going outside to entertain manchild) and he spewed the following words at me "I'm going to go spend time with my son.  He is my priority, and if you don't like it, you can just f*ck off and stay inside!"  They were like a married couple - my ex husband even became furious with his son one evening because his son went to the park for hours and "he's not here to help me with supper!"  And even though he was mad at his son, he took out his anger on me - he always did that:  get mad at son, abuse wife.  Ex-SS even told his daddeee things I didn't do just to get his dadddeee mad at me (for example, he told his dad I kicked and threw their cat when I did not such thing).  His dad always took his side, much like your DH did with his son.  He always told me his son was first, always, and was more important to me.  I wish I had listened and not wasted 9 years of my time.

You definitely have  DH problem.  But, I can tell you from experience, I doubt your DH will change.  I am so sorry you are experiencing this and I wish I had positive, helpful advice.  The only advice I can offer is to leave.  I left and am so much happier.  No more being humiliated and treated like sh&t, no more walking on eggshells or hiding in my room just to try to relax, no more spending money on two grown men who hate me, no more trying to earn/buy their love when it was never there for me in the first place. 

You can try to put your foot down and insist he stop his son's behavior and you can even try to discuss this behavior with the son, but I think they'll both just band together and retaliate against you.

Of note, any parent who allows their kid to talk to ANYONE the way SS talked to you is a failure as a parent.  I can tell you, if I had spoken that way to my mom or anyone, my dad would have whooped my butt - and rightfully so. 

I have a whole string of posts about the hell I went through - please read and message me if you need support.  I feel your pain more than you know. 

Please put yourself first, you deserve better.  Keep us posted.  **HUGS**

Oh Honey, My DH isnt perfect by any means, weve struggled a lot with this whole situation. The one thing that he has never tolerated is the kids disrepecting me. Our daughter or SD. The best suggestion I have for you is you need to put your foot down with DH, in private. Tell him (in your own way) that you will not tolerate being spoken to like that, and if hes going to allow SS to disrespect you like that, then your going to stop doing all the little nicedys for him. being upset is absolutely understandable in this situation, but being disrespectful isnt going to get him what he wants and its not okay. also DH passing the blame to you for "pissing him off" is bullshit.