Mark
CreativeMountainGames.com
He refuses to go away because friends are supposed to be stuck together until they die, which sucks because he's not exactly the kind of person I can spend more than a few hours with. He doesn't respond well to criticism either, and generally speaking calls anyone that makes a useful observation of his behavior a bad friend, or not a friend at all.
Just tell him he is no longer welcome. You've been left no choice.