tufchoices---I can tell you from my own experience that kicking one of your children out of the house is one of the hardest things a parent has to do!!
You will feel better and stop your own "guilt trip" when you realize that you did the best thing you could do for your son at the time. It was out of love and concern that you did it. It was loving (though he won't realize it until he stops drinking). You don't have to feel guilty for doing the best for your child.
We parents usually learn this hard lesson about not enabling (with good intentions, of course) through bitter experience--just as you just had.
My heart goes out to you--but just keep reminding yourself that you did the best thing for him. (Hold your ground and never let him suck you in again).
He will survive. If they are resourceful enough to get the alcohol--they are resourceful enough to live where ever they have to. They won't become responsible until they have to.
dandylion