fear is what motivates us to enable others. everything you have done has been enabling because you have a certain fear of how his actions are going to affect you. Let Go and Let God and believe in yourself, take care of yourself, and quit putting yourself in the line of fire for his sake. don't be guilted either as being the only person "close" to him. hitting bottom can also be seen as you taking your fluffy pillow out from under his a$$. him not doing what he needs to do may be just what it takes for him to hit bottom.
one good cure for enabling is detaching. you could tell him, "it is your choice" and then you LET GO and LET GOD! you can do it.