Sadly he is using you since he has no where else to go. I know that might sound harsh and hard to take, but from what I gather he just needs you so that he can have a place to stay. I'm not telling you to leave either, I'm just telling you that you are in a bad situation, that will only get worse, since alcoholism is a progressive disease (which I'm sure you know already). My husband is an alcoholic and I do not want to leave him either, so I just "deal" with it, so I understand what you are feeling..but you are (and I am too with my husband..but doing a little better) enabling him. Try to detach yourself from his disease the best that you can. Definitely do not give in and buy him alcohol or do anything that will "help" him. I'm still learning myself, and you will too. We all understand and are all here for you.
Take care of YOU!