Ya know, you can only do yourself, you can't do your friend. It sounds like your friend needs some therapy, and he needs to start taking control of his own situation.
Tell him how you feel, give him a copy of Seligman's Learned Optimism, and yes, start distancing yourself.
Boy, you're hard on yourself, with all this guilt and all. You're growing, he's not, that's it. Are you his therapist? Your relationship has been all about him, him, him. That's not sharing, that's not communal.
Move on. And if he gets it together without you, so be it. If he doesn't, so be it. Get busy living.