Hi! I am saying this to you but this goes for anybody who is trying to help a person with a serious mental/personality disorder. You. Cannot. Help. Them. Only a trained therapist or psychiatrist can help them. In fact, not only can you NOT help, but you might accidentally exacerbate their condition or become an enabler.

Such a person is not fit to date or go into a relationship, unless his psychological problems are cured or under control, and he or she is under the supervision of a trained doctor/therapist. If your friend is still showing psychotic behaviour then he should immediately see a doctor about it. Either way, you are not competent to help him, and the best thing you can do is walk away from him, which you have. You did the right thing, and I think it is for the best if you don't try to help or fix such persons in the future. Instead, try to find healthy, well adjusted people to hang out with.