My friend mad at me because I asked him to sign a contract to pay me back on rent, what to do?

A friend became my roomate, and we have a planned that once he gets a job he will pay back the rent hat he owe's me. (I been paying the rent, once he get's a job where gonna split it, and he'll pay me back the months he missed) I asked him to put this in writting for me for my records now he steaming angry thinking I don't trust him. Making uncomfortable living conditions, what can I do? He really offended