MIL HELP/RANT

So I cut my mil off from contacting me. She has done and said some things that are just inexcusable and our relationship is beyond repair at this point. I did not make my husband cut her off from him, because that needs to be his decision, even though nothing would make me happier if he did cut her off. ANYWAYS, my sil is graduating this June and wants us to be there, I 110% want to go to celebrate her. It will be my husband, our son, my two SILs, their grandparents, my mil her current husband and their 5 year old. I have zero problem with everyone else and want them to be able to spend time with our son, since only my SILs have met him. However I don’t want to be anywhere near my mil nor do I want my son near her. My husband doesn’t want me to go if there is going to be problems but said he will be taking our son no matter what. I’m not the one who started drama, my mil did. I’ve never said anything negative to her but she on more than one occasion has verbally attacked me, tried to make up lies about me, get me arrested for having MY SON. She is certifiable to say the least.... so I told my husband I’m not comfortable talking to her, being near her or having anything to do with her. My husband still thinks she should have a relationship with our son, when I tell him no with valid reasons why he tries to say then my family can’t have a relationship with our son cause it’s not fair to his family. I’m not cutting ties with his whole family, only his mother for very valid reasons, so why should my family who’s done nothing wrong be cut off?? My question is what would you do? I really want to be there for my sil and to see their family but I don’t want to be anywhere near his mil nor do I want her near our son.

The reason I’m not okay with it is because she has made it where I don’t feel comfortable or safe being near her and I can’t trust her to not only be alone with him but that she won’t kidnap him, due to things she has said and done. I shouldn’t be punished/fear for my child and my own safety because of my mil