old roomate

My former roomate/co-worker wants to sue me for past rent on our former residence. me him and my girlfriend moved into a place together and lived there for a year. when we moved in me and him agreed to just split the move in cost (first last and deposit) 50/50 since our employer was going to finance the money interest free. only me and him signed the lease and for the remaining 10 months we split the rent 3 ways. now after we moved out and things grew sour, he wants me to pay him for his half of her share of the rent for the first and last month since we only split it 2 ways when we paid for move in cost. I am just wondering where I stand in a legal standpoint, If he had mentioned it when we moved in or at any point I would consider paying him and getting it over with but he is a total **** and dont want to give him a penny. He just decided one day that he can make some money off this deal. he has also sent me threatening text messages, I personally dont care all that much but can that help me in court?

You are responsible fully to the lessor/landlord, but if you all agreed a different arrangement as to contributions monthly etc. then you need not pay him.

Keep and and all evidence that shows what you agreed--bank records etc. too.