Boyfriend is depressed

Please help! My boyfriend is suffering from depression/ mood swings and is irritable, hates himself, hates his life, but apparently loves me and wants to marry me.

he cries when he is sad, he drinks a lot of alcohol to feel better and in the past has punched walls, cut himself, threatened to abuse sleeping pills and is so miserable.

we have been fighting a lot recently and don't have resolution in our arguments. We both started seeing our own therapists. He said while he was drunk how much he wants to marry me etc meanwhile I'm crying as I am forcing him to vomit because of the whiskey he has drunk. What can I do to help him? Is it possible he loves me if he doesn't love himself at all and often says he wishes he was dead?