I do not have this problem, my SS21 is accepting of me, and DH barely does anything with him anyway.  But I always try to imagine how I'd feel if he allowed SS to mistreat me/exclude me and just went ahead and attended events with him anyway. And he also allows his sister to do the same? And why, because you are his wife and they don't like that, and for no other reason (ie, you haven't mistreated them in any way)?  

He doesn't like conflict, so he doesn't say to them that you are his wife, and he expects them to treat you with respect or he won't be attending events either - I would have a very hard time with that, myself.  It's one thing for him to go out to lunch here and there with his kids without you, but completely different to attend family gatherings and allow them to treat you badly.

Is DH. Not the SK,  He should put his foot down and stop all of this. Either you both are invited or no one goes.  It's a war.  "You can't make deals with terrorist ". Your DH is making deals, he has to stop.  You totally disengage from SK.  You just go to show your place in the family 

I am sorry you are having a difficult time.

As noted above, the issue is your husband. He has decided to pull you into the fire pit AND expects you not to feel a thing.

You have a decision to make...stay and find a way to manage. Or make plans to walk away.

Sorry to be so cut and dry. I know there is a lot of stuff in between that. You do have power. 

I tried to be a positive for 12 years; dealt with much of what you deal with. Wasn't invited to events with my DH, was ignored, spoke down to, shunned, etc. I spent way too much time trying to fit in. Nothing worked. I continued and ultimately, let myself get almost totally destroyed at my husband's retirement party. From that point, it took me 3 years of counseling, group studies, praying and reading anything I could get my hands on. My marriage almost ended. I finally made it out of the fog. A book that greatly helped me was "Forgiving What You Can't Forget by Lysa TerKeurst." It is Christian based but I think it could be read from a secular POV. (I never push my faith...just sharing a great book).

Things we've/I've done: DH sees his adult kids away from our marital home. I am completely cut off from DHs kids; 4 years now. I do not get involved in DH's relationship with his kids. He rarely speaks about them to me and when he does, I reply with, "oh that's nice" or something very generic. I do not ask questions. He has had it out with them and while they are still in relation, it is very strained and they know why. He misses a lot of their big events because I can't/won't go and that's on him. I truly believe had he took a stronger stand early on in our marriage, we would not be where we are today. But he groveled over the little morsels his kids gave him, thus encouraging their behaviors. Your DH has a lot of ownership in the current problems.

Now that the BM is dead, I know they'd like to see their dad more but without them making some major changes in behavior, that won't happen because DH hates traveling without me. I don't hate them and I have forgiven them but forgiveness does not equate being back in relation. One good thing for us is the majority live across the country. The one local one never visited his dad anyway. 

I know how hard it is to "not be liked for no reason." I encourage you to find a good counselor to help you navigate your journey. That, along with learning from other SMs dealing with high conflict SKs and exs has really helped. I refuse to give my goodness to people who don't respect me. There are so many others that need that from me. I make quilts for Veterans and friends, donated quilts for raffles to help dog rescues I support. While I'll probably never have bio grandkids, I am the neighborhood Auntie to two sweet babies who have multiple quilts of mine. All you need to do is stop, look around and you will see so many people out there that need/want your love....time to start looking. Best to you. It's not an easy journey but I'm on it and I'm doing well now. Hugs.

She is very toxic and blames me for "losing her father" to the point of calling him "just a sperm donor". That was in September. This past year I have tried with her. Sent her bday presents, took her out to lunch, orchestrated dinner with her and dad. She was no contact after graduating high school and when she lived with us she would shun me and act disrespectfully, and we had 50-50 visitation. So its been up and down with her. Shes just interested in parties and drinking and hasnt worked for almost a year until recently when she has decided to move off her mothers couch and away about 4 hours north. You can read my blogs about the Feral Forger/Winona Chronicles for my story.

But Dh would never in a million years play happy family with her. I encourage him to spend time outside our home as she is not longer invited after her trashing me. Luckily SILS realise that she is a liar and manipulator, and they wont live with her either! MIL and FIL are deceased.

I do not spend much time worried about her at this point in time - hopefully she moves forward in her life away from me. Hopefully the cousins that believe her stories learn their lessons. Im going to do my own thing and hope for the bestt.

Which was similar to this., I commented that the worst betrayal from my ex DH was to continue hanging with SD and BM, the two people who were so cold and calculating towards me.

My hopes and dreams of a quality DH were dashed. I always thought that a couple was a team, like on the SAME team. If someone hurts their spouse heads would roll NOT their asses kissed.

Its hard to salvage a marriage when your DH continues on as if everything is ok. Everytime he walked out the door to spend time with people who hated me because I breathed, my heart broke just a little bit more.

That is why so many step families are flucked at the beginning, if the original family causes problems.

Blessings