Can I asked have you lived together long. This kind of sounds like my ex as soon as we started living together he changed and I was the one who ended up leaving. All I can say is yes get out before things do turn nasty and if he wants you to go back when you have left steer well clear as I know when In love you want to do anything to try make it right. I really do feel for you but you will meet the right person like someone else said you will look back like they did and what I have and think wow what was I thinking. Just speak to the landlord and make it clear you won't be living there and that you shouldn't have to pay the rent maybe even seek legal advice. I know this is very hard but stay strong spend time with your friends and family x