My fiancé’s ex is crazy and I don’t know what to do

Recently I joined a group on Facebook for moms. I’ve noticed that every single post I make is either immediately deleted by an admin or the comments get shut off as soon as they become positive or supportive. I never really thought anything of it but I did wonder and question why questions about my children weren’t being allowed on a mom‘s group!

Today I made a post about my children and trying to find local children to meet up with with. The post was immediately deleted by an admin and I had no idea why. I did some searching on the group and found a list of admin‘s and ironically one of them is my fiancé‘s ex. It all came together and it clicked, I don’t really know what to do. He seems to think I should tell the group about her but I just feel stuck. What would you do?