How to help a friend who is pushing you away?

I have a friend who has a lot of issues with his feelings because of his past (with family and relationships) so he keeps his struggles buried, instead he abuses of excess (alcohol and sex). We started dating a few months ago, but when he started feeling something for me, he pushed me away... and I suffered a lot, I had to go to a doctor to get help with my sadness. I stayed away from him for a couple of weeks to get stronger, but my intention was never to disappear. He is afraid of feeling because he says that the people he loves always go away, so he has such a strong mentality to never open up and be an ass with girls. Now that Im much better and have the strength to come back to his life, he is in a really bad shape, he says he fell in love with a girl from work who is a complete ass, and he knows it, shes only playing with him because she has a boyfriend, a recent exhusband, and she just wants attention, so she keeps playing with him. We talked recently and he said that he was going to become the persons he was in the past, abuse of sex and alcohol and he is going to push every friend that hes got away, because he says that the help theyll give him its just pity. He also said to me to step back and go away, that he was going to drown himself in his own hell.... what should I do? I have this feeling to not let him go, because he really needs help, and hes never going to open up with anybody else about this crisis that he is going through. How can I help him? Show him that Im by his side and that I want to help him? Right now i think he is at the peak of his breakdown, but I think nobody is strong enough to go through this alone, specially because he is not looking to get any better but to drown himself more and more in this misery