Sorry if this is a little sparse on details, don’t know who involved with this regularly browses reddit

A little over a year ago, I met this dude (let’s call him Dave) through a club at school. We talked a bit and I always thought he was a little strange, but not malicious (though he would get annoyed and proudly declare that he knew he was an asshole). Fast forward a couple months and I become friends with this girl (I’ll call her Kate) who happens to be friends with Dave.

Dave sexually harasses Kate, she’s obviously disgusted and I am too, so we both sort of do our own thing, still talking to him more out of necessity than want. The months go by, Kate and I get closer and bond over mutual interests, while Dave is obviously jealous that we became so close so quickly. With many smaller comments and literal tantrums leading up to it, it eventually gets to the point where he says to me (only me, not the two of us) that I need to stop bringing up my mutual interests with Kate because he doesn’t enjoy them too. I tell her and she’s obviously like “Fuck him we’ll do what we want” and that was the end of that. We talked to him occasionally, but only when we had no choice. Once he graduated I responded to his texts, but as they got progressively more strange (talking about like “How much I loved him” and stuff) I just stopped. (If I had to guess, he went to texting me because all his existing friends ghosted him earlier, but maybe I’m wrong.) AITA? Or is there a point where enough’s enough? I don’t want to associate with someone who’d treat a close friend of mine so poorly, but I also don’t want to cause a conflict that will definitely affect more than just myself

TLDR: “Friend” Dave sexually harasses my friend Kate. Months go by, Kate and I become closer friends, Dave gets pissed off and clearly shows that he doesn’t like us being friends. I get fed up with everything and ghost the dude to avoid a conflict that would affect more than just me