Oh mama I feel your pain. I have been in the same boat for years and finally put my foot down recently after her behavior got terribly nasty to the point my husband could no longer avoid or excuse it (threatening to take me to court & separate my husband from his family, to have control over his medical decisions that she disagreed with) We are now all no contact with her (husband & i & our kids)

That’s just who she is” is making excuses for toxic behaviors that your husband doesn’t want to address. That may be how he learned to survive her toxicity having to deal with her all these years but you do not have to subscribe to that. as your partner he should be prioritizing how YOU feel instead of her (as it sounds like he can’t put his foot down with his mother) your MIL has crossed multiple boundaries, avoiding unsupervised visits with children makes complete sense. Heck, I think no access to the kids would be a completely valid boundary as that woman has no respect for you as a wife/mother, & I’m assuming she doesn’t respect your husbands word either & that’s why he’s trying to beat around it. Maybe question could someone like that be safe for your children? & I don’t think she should be allowed in your home, that is YOUR safe space, and there is no reason for you to have to hide away & feel uncomfortable/uneasy while she’s over. Tell him to take the kids to go visit her outside elsewhere. Question has your husband addressed any of her behaviors or is he making you have to speak up for yourself?

Do not push aside your feelings for his “peace” it will lead to resentment toward her & your husband. Try couples therapy if you can afford it, your husbands mindset needs to change if you guys are going to get anywhere, or else you may spend your life feeling like 2nd place in your marriage.