I'm going to keep this brief but I need opinions! Ok, my sister and her boyfriend of 8 years broke up a week ago. She moved home with our mom and he's moving home with his. ( they are 22 now)

I've known this young man since he was 14!! We are very close! My sister wants us to never speak to him again. What would you do? Mind you my sister has bipolar and depression so even when I see him and talk to him I don't tell her. Is it wrong? I still think of him as family. And he's devestated by the sudden breakup!