Block him on all fronts and block his friends too. If you keep interacting with him, it is just going to stress you out, and he is going to keep acting the way he has been. I really think it would be healthy for you and him, to cut contact. If there's someone you can talk to about him, at your University, to alert them to his behavior, like the counseling center, maybe, but really, cut contact with him and his friends. He is not your responsibility. (((Katie97)))