Do you think he loves me even if he is married?

You are setting yourself up for heartache. Think about it: he's a married man with kids. Do you think that he will leave his wife for you without hurting her and the children? If he did leave her what kind of relationship would you have? You are a teenager with many years ahead; education, career, marriage, children. etc. Your relationship with someone should not be a "secret" - you should be proud & happy to share it with your family & friends. Please think things through - your happiness is at stake.