Hi, thotful. This is a difficult position to be in, for sure. With my own family, I just had to say, "I love you, but I have to get off the merry-go-round." Growing up, we were always expected to sweep everything under the rug. I see the signs in stores that say, "Remember, as far as anyone knows, we are a perfectly normal family" and I can't see the humor that was intended. When you've grown up in an abusive or addiction-afflicted home, that statement has a completely different meaning-- it touches a raw, painful place where we stuffed all of that garbage and our feelings until we just stopped feeling. I finally had enough and decided to work on my own recovery, cutting off contact with my AM and anyone who was "on her team." Right now I will talk to a couple of family members on a need-to-know basis, but my boundary is talk about my AM. It's not productive, and I refuse to engage in their special brand of enabling, codependency, and toxicity.
Acceptance is just that: accepting that they believe what they believe and that you can't change it. You don't have to agree or like it, but you are accepting what is. Letting go is learning to disengage from their drama and being ok with your family as it is. It's ok to love someone but not talk to them. It's ok to focus on the family you've built. Really. It's ok.