My ex's sister invited me out to eat a pizza this Friday night together with her boyfriend. My ex is now dating someone and for some reason I'm afraid he will come too with her. I don't know whether his sister knows that we dated (it was a super weird situation) so I don't know what to tell her. Me and the guy no longer speak because he disrespected me so he's dead to me but I'm scared to tell his sister about him. What would you do? I can't tell her "look, don't ask me why but please tell me if your brother is gonna be there too".