Need some advice

Am

Long story short - about a year ago my husband and I decided we needed to cut my FIL off. He had started doing meth, was hiding it in the family home, where his grandchildren played, sneaking around with women while he was “at work” he pulled a gun on my MIL during a fight, busted down some doors in their home, he constantly lies, we just don’t trust him anymore and add to that all of this new scary stuff. Anyways. We had our first baby shortly after and decided that we didn’t want him to be around that.

For awhile the rest of the family was feeling the same, he wasn’t invited to Christmas or birthday parties or anything like that. But now my MIL’s mom has started inviting him to extended family functions so we haven’t been going. My SIL was completely against him being at functions as well but the grandma and her mom have guilted her into coming around little by little until she’s okay with it now.

We just got an invite from her to a party and after we said we’d be there she told us that the FIL was going to be there too.

I’ve never wanted to cut the siblings off but that’s essentially what’s happening. My husband absolutely doesn’t want our son around him, but he wants to see his siblings and nieces and nephews.

My heart is broken for my husband because he loves his siblings and his mom but they’ve all chosen this man because he’s made flowery promises of it “never happening again.” Side note: He’s been cheating on my MIL for years and we found out recently he’s been in trouble for drugs several times before so I don’t believe him when he says he’s suddenly changed. I would like to see some actual effort from him before we start to allow him back into our life.

I don’t want to hurt his sister by saying we’re not coming then but I don’t feel like we have a choice?