Lucidiotic

Hi there, I'm new here and I was hoping basically to get some advice. I know it's rather selfish to jump straight in requesting advice when I have contributed nothing but I'm feeling rather desperate so I'll continue on...

I'm 21 and my partner is 26. We've been together for over a year now but have been inseperable for two and a half. He has a drinking problem which he says he realises is a problem but doesn't seem to yet accept it as something that is destructive. I don't like to judge him as I have mental health issues of my own but I'm not sure how I can help him anymore. He drinks 4 or 5 times a week, and each time will get completely innebriated.. he'll act insane.. jealous.. he'll be aggressive and he tries my patience to no end. He doesn't remember the next day.. and when I tell him he is full of apologies and tells me it's going to change. I worry about his health, not just his behavior.. he can't eat or put on weight. I have 'tried' to end the relationship many times before but I get seduced with the promises of change (my fault I know) but I really love him and each time I feel confident it will be different. When things eventually fail I'm angry and it does him no good, nor me. I really don't know what to do anymore.. is my staying with him unhelpful? I love him so much but this is hurting me badly. It's impacting on my life in a big way.. but I feel like i'd just be deserting him to drink himself to death if I break up with him.

I don't know whether I can fix this.. does anyone have any advice for me? It would be greatly appreciated.
Thanks for reading.