new member here, I know, I know, I am emotionally immature, I cannot control other people's behavior, yada, yada, BUT and a big but. Why DO I always have to be the grown up? WHY do I always have to "let it go"?

Backstory. DH and I got together 14 years ago, married a few years in - 8 year in, since I was very careful about who got to be with my bio kids, two of whom were still home at the time. We live in my house, but that only happened a couple of years after we started dating. His DD's were h.s. and college aged when he split with ExW - we began dating that fall, and for the most part it was "okay". The youngest (30SD) was creepy, anytime she was around, she ignored my side of the family, and every now and then would pet DH and say"hi dadee" in a little girl voice, and eventually she moved to the big city to run her drama in all sorts of f'ed up relationships with married or otherwise unavailable men. Gorgeous hardworking young woman, but weird. I haven't seen her in over a year. The other SD(33) was also a PITA until she found her SO - her SO is midwestern sensible and nice, and we had some genuine moments for a few years there. OSD never lost her incredible entitlement, but it was tempered for a bit. I thought OSD might be growing up. I hung in there, ignored the long winded stories of favorite pets and "daddy, remember when" shit, and the particularly weird "sister" thing they have going (matching tats and all that). Somewhere along the line, DH "loaned" OSD & SO a pretty significant chunk for a down payment on their first home.

Fast forward to Christmas 2014. Youngest bio is mentally ill, not violent,not even unpleasant (he'd rather cook and clean up than sit at table, and he's never caused scenes) just chronically suicidal and very sad. After horrible drama with him and the legal system all fall (during which time my dad died, my mom entered hospice), I was able to bring him home last year on Christmas Eve at the end of a very long and upsetting day. DH told Skids BS was going to be here, and in response SD's texted their dad and refused to come. Not a word to me. I was particularly hurt by the fact that OSD is amental health professional - who knew there was nothing to fear (admitted that later) and we had many other people invited to see the SD's and the YSD's SO who was coming to meet the family for the first time. I offered to take BS and clear out for a few hours so they could come by for aps or desert and honor the effort of the out of towners who had gone to such trouble, but they "didn't feel safe". Fine. eff you, I'm a really good cook and you missed an amazing meal. I decided I was done. I'd worked really hard to be "okay" with all the gaslighting and passive agressive stuff for years and find ways to build common ground and be supportive, BUT apparently there was only ever room for one family - DH's. got a stupid email almost a week later, a non-apology, "gee sorry we didn't see you at Christmas, no one's fault what happened, but we just weren't ready to deal" apology. They basically were pissed that I ruined their happy Christmas show off SO's to the out of town guests. I didn't respond. Didn't say anything to DH after Christmas and since he was copied on the email, nothing about it, other than I didn't consider that an apology. Saw OSD at Il's for a spring holiday, but that was it. I avoided conversation as much as possible, which wasn't hard because she just wanted to talk about herself to the other people there.

DH has been mopey about me not wanting to be around the SKids - and at one point when he was pushing me about it, I told him exactly how I felt and that I wasn't willing to work that hard any more to put into relationships that were so one sided. It got worse this fall, OSD and SO are getting twins this spring. DH is all gaga and wants me to be all happy excited grandma (which I was really looking forward to before a year ago) and got all puppy dog sad when i told him that those are his GKs, not mine. A few weeks before Christmas OSD decides we should go to mediation or family therapy to 'work through it" or I can't see her kids. My response was a polite, but clear "no". And then the gloves came off, she's starts texting and emailing dad about how rude I am and writes me a poison pen letter informing me that I'm too sick to be around her family. (the family in which, the kids aren't even born yet) Lots of emergency marriage counseling later,DH finally man's up and informs (as I had asked him to weeks earlier) osd that I'm off limits and no more name calling. But now MIL and FIL are all (because DH told them) upset over this, DH is sneaking around to see his DD and not telling me, "because it hurts you" - how f'ng patronizing can you get? - and I am sitting on this for 6 months before I decide if I walk or not. I hate the idea of losing DH over this, but Osd fights dirty. Already using her unborn kids, and that's not going to change. I don't want to be in the lives of this entitled woman and her family. I don't want to associate with anyone who would use children as a bait or a weapon, but I also don't want to have to sit on my tongue while DH and DH's family allows themselves to be manipulated and manipulates me in turn.

I warned you it was a vent. I hate the idea of OSD getting away with being an ass. And I hate the idea of having been so frugal and underwriting much of DH's living expenses while he forgives loans and doles out more cash (BTW,osd and her SO got money from Exwife and SO's mother so they can buy a bigger better place - still haven't paid off the loans for the last one) DH is basically a good guy, and we get along in every other matter but this one, but like so many BDs cannot see anything wrong with his kids. And OSD is increasingly more insufferable (based on word from MIL), because getting twins makes her all that much more special. But that's okay, because after all, she's young, she's always been emotional, she's just "lashing out" because she's hurt and I'm a grownup, I should just get over it. Where's MY satisfaction? Who's defending my story here?

Advice welcome. Failing that, single malt on the rocks.