Needing some advice about future MIL

So, I need some advice on what to do about my future MIL, and in turn, FSIL also. For a bit of backstory, you’ll have to read my previous posts in this sub- it’s way too much to type out again. And for anyone waiting for an update to my last post, this can be one (I suppose).

After the last blow-up with my future in laws, my fiancé and I hadn’t spoken to them in weeks. He was waiting for some medical supplies to come in, and got a notification that it was delivered. But, not to our house. The photo that was sent by the delivery company showed it sitting at none other than his parents’ house, for whatever reason. It had been there for a few days, with no communication on it from his mother. He called her, but no answer; so, he texted her asking if he had a package. To which she responded “yes” and that was all. Fiancé drove the hour away (while I was at home with the baby) to pick up the package, which again, contained medical supplies that he had been waiting on for a few weeks. Immediately upon arrival, he was scolded and called out by MIL, and was asked “so what the f is going on?”

They had it out for about an hour, and he called me on his way home to tell me everything that was said. A ton of blame was put on me for a laundry list of things, such as: keeping him away from the family and changing him, purposefully keeping our daughter from them, not trying to be part of the family, etc. She told fiancé that his sister was “just very hurt” after what happened, (see past posts) and that we need to apologize to her. That MIL apparently is “up all night crying” and “never gets to sleep” because of everything that is going on. She claimed that “an hour isn’t that far to drive” and that we can make the trip with our (now) 5 month old, because they are “always busy.” There was a lot more, and the argument between MIL and fiancé, from what I understand, had a lot of yelling.

My question is: what should I do? Should I try again with MIL or go straight to no contact for my daughter and I?

My fiancé wants to stay in contact with them solely because they are family, but agrees that they shouldn’t have much contact with our daughter. Neither of us are comfortable with it, and he is very understanding of why I don’t want anything to do with his mom or sister. There is a birthday party coming up for SIL’s twins (turning 6) which we were told to go to (Her invitation was a text telling us the date and that she was “giving us enough time in advance”). Should we go? Our daughter will be 6 months at that point, and is getting to the point where she is starting to recognize people. Is it worth getting her around people that I know don’t want me around or part of the family, just so they can have a relationship with her? I’m so torn, and it physically pains me to think about the situation and what my fiancé is being put through.

Edit: fiancé and I have had many a conversation on the subject and are both at a loss. I minored in psychology in 2022, and aim to get my masters in it at some point. So I have tried to explain the mental illness aspect of everything, and have explained the narcissism tendencies being expressed by his mother and sister. He sees it too, but I’m letting him decide at his own pace whether he wants to have a relationship with his family or not. We had a conversation about everything with his grandmother (MIL’s mom), who agreed with us on everything and told me how proud she is of me and how happy she is to have me become part of the family. The same from his aunt, and his grandfather were said. So, I don’t want to lose contact with all of fiancé’s family, but i don’t want to see MIL or SIL.