What do you do with a friend...

I've remained close with one of my exes but from time to time it's painful. Tonight he obviously needed someone to talk to, but when he drinks he's an absolute ass. I listened to him for a long time not tell me what was really bothering him but rant about all sorts of irrelevant stuff, but it quickly turned towards him destroying me. After 30 minutes I was in tears and told him that I was willing to listen to him about his problems, but he cannot attack me like this because he's hurting or because he's in distress.

That I'm willing to listen to what's really bothering him but not willing to have yet another fight because he's a drunk ass.  That's when he started to cry and get all paranoid on me.

I mean how far should you go to help a friend? Is it really helpful if you let your friend destroy you each time they have a crisis? When is enough enough? And how does one break those pattern?

I do love him always have always will, but I cannot let him hurt me like this all the time. It was the main reason we are no longer significant others. The relationship was unhealthy for me, and presumably for him as well.

Now I'm sitting here still upset because I know he's hurting and I'm not being there for him. I wish I knew how to be there for him and not have to pay that price. I'm also sitting here upset because he said some nasty stuff and while I know it's the alcohol talking, it still gets to you after a while.