surely you have SOME dealbreakers when it comes to relationships? to be blunt, and i know you didn't share EVERYTHING, but i failed to find one single redeeming trait of this guy!!! he's a drug abuser and a people user.
it's time to stop. you are only making yourself miserable and inadvertently enabling him to keep on being a total jackass. get him out of your house, off your phone plan, and BE DONE. and get back to living YOUR one great life! stay sober, get back to school, and don't allow anyone to treat you poorly or take advantage of you again.