Don't pay your half of the rent until he coughs up some cash for the time he's imposed on your time in the big room, and tell him unless he reimburses you, you will live there rent free until the landlord kicks you all out. I'd do it in a heartbeat, since it's the only way you will actually get what you payed for, one way or another. He sounds like a real ass face, but not having a place to live or paying the rent by himself might shake loose his brainstem from his anus and get him thinking straight again. Good luck