Did he do it or not

I have been seeing this guy for like a month . He told me he had sex with my roommate and I asked him numerous times . He jokes around a lot but he said no it really happened, will you stop talking to me if I did? then I asked him are you serious. He said no I'm just kidding then is calling me crazy for asking about it or believing it. We are exclusively seeing each other and I am not talking to him if it's true . Do you think he did it or no.