I agree with the above posters. Your bf needs at least 6 months to a year clean before considering a move back in. Often drugs users relapse. You know this. You know how hard addiction is to break. It seems you are not living for your son necessarily, but should be able to tell your son you are communicating with your bf and are considering getting back together. But again, I would wait a much longer period of time and like someone said, he needs to earn his way back in.