In laws are refusing to see us unless we also agree to see abusive MIL, and idk what to do

This is so fucking ridiculous and I’m so infuriated by it that I’m shaking as I type this. I can’t even go into the entire story of what she’s done because it just makes me too angry. But basically my MIL has been horribly emotionally abusive to both me and mostly to my husband, for the past several years (not to mention sexually abusive to my husband as a child...) The last time we saw her was a year ago. We met up with her for dinner because we wanted to try to make amends and invite her to our wedding. Instead she showed up drunk and spent 2+ hours screaming at my husband for being a “disappointment” and how she was ashamed to be his mother. This is only the most recent instance... but basically just imagine about 3 years worth of shit like that.

Since then she’s “tried to make amends” by which I mean, she sends him ecards on every holiday, and then plays victim to the rest of the family because my husband refuses to answer her messages. We’ve tried to make amends with her at least a dozen times over the past few years. Sometimes we’ll even be on good terms with her for a couple months. But then she always ends up beating him down with more abuse and claiming that her being nice for a couple months was “faking it.”

There’s only so many of her bullshit apologies he should have to take, and after this past time, my husband reached his limit and wants nothing to do with her anymore... now, and in the foreseeable future.

The issue is, we are going to visit my husband’s grandmother next month (his grandmother, his parents, and the rest of his family all live across the country from us). He and I are both very close with his grandmother and she is old, weak, has Alzheimer’s, etc so she can’t travel. So the main purpose of the trip is to see her, but of course we’d like to see his other relatives while we’re there too (his dad, brother, grandfather and other grandmother, and aunt/uncle/cousins).

His dad is telling us that he and his brother and grandfather are refusing to see us unless we invite his mother (not sure about his other relatives yet). Their logic is, it “isn’t fair to her” for them to all go out to dinner with us when she isn’t invited. When we reminded them that it wasn’t fair for us to have to endure more of her verbal abuse, his grandfather says “if we could forgive Japan after Pearl Harbor and Germany after the holocaust, you can forgive your mother.” I’m not kidding. He ACTUALLY said that.

My issue is I just don’t know what to do at this point. I am so, so sick of this family of goddamn enablers. Of them acting like her abuse isn’t that bad, and shaming my husband for having boundaries and protecting himself from her.

However I know he still wants to see the rest of his family. I know that’s important to him. And if his mom comes, she’ll either (1) be nice and the rest of his family will be happy or (2) be awful and then at least the rest of the family will be witnesses and get off our backs about it, at least temporarily.

Though I know subjecting him (and me) to this stress is ridiculous, and part of me just wants to say fuck them, if they don’t want to see us because we refuse to have dinner with my husband’s abuser, that’s their loss. But I don’t know if I’m saying that because it’s what we should do, or if I’m just too caught up in my anger with all of them.

Please give me your thoughts, what would you do as the wife in this situation? And don’t say “leave it up to him” because he’s so frustrated and vulnerable with this entire situation that he can’t possibly make a decision on his own, and I know he is going to be looking to me for answers :( I’m just so upset and so close to the situation that I know I’m not thinking clearly either and I want to make sure the advice I give him is actually good and not just based in my emotions.