My room mate's girlfriend broke up with him like 2 months ago, and he keeps trying to get back with her. About a month ago I found out through mutual friends that she had been cheating on him for a year and a half with someone else. I believe this like 95%, but I hate to gossip. My question is, should I tell him, or just mind my own business? He keeps taking her out to eat every once in awhile and gets pissed off, and hes been a depressed asshole since.