Dating An Older Man - Is He Right To Make Demands?

I am 19 and I have been having an affair with a man in his 40s for about a year. I really like him and I would love to have a proper relationship with him. Right now he only ever sees me for sex and we can't do anything together in public as he has a wife and family. He says he does not love her and he loves me but he isn't prepared to leave her unless I agree to move in with him straight away and get engaged. I don't want to get engaged as I feel I am too young but he says he won't leave her unless I do. Am I being too harsh wanting him to leave her and date me normally. I know he has a lot to lose but surely he should trust me?

Updates