Am I being a crazy boy mom

I have 5 kids. All boys. My oldest(20) has a fiance and I don't really like her. I need to know if I'm overreacting though or is this weird.

We all got together for a Christmas party and was in the group loudly talking about how my son and hers bedroom business and said "I think you are a little gay. I stuck my finger up your ass and you got hard." First. Children were around. Second. Why are you saying that at loud. Third why say that all. He got mad and they stepped out to argue

This happens a lot between them. I don't understand why she said that because it clearly seemed like her goal was to embarrass him.

Am I being a crazy boy mom or is she low key toxic because she says things like this and tries to embarrass him a lot.