How to help my teen friend going through many things?

Okay so he is gay and has been going through many tough things such as OCD(obsessive compulsive disorder), bulimia, he has even started cutting himself? He has recently started thinking about suicide. How do I help him? How so I let him know he is not alone? And how do I help him change his thoughts on all of this? Please help me as fast as possible. I really care about him and I wouldn't want him to hurt himself.