Should I ask him out?

I go to boarding school and very quickly developed a strong friendship and crush on a nice boy. At first I was hesitant because I'm friends with his ex, but she says that she doesn't care. Then I learned he had another girlfriend. I suffered through meeting her and we didn't get along. The boy broke up with her because she wanted him to stop being friends with me. Now he's single and so am I. He offered to be my New Years kiss even though we are countries apart for New Years. He said he'd owe me one once we get back to school. One big problem, my roommate hates him. He may have said some bad stuff about her even though he claims he didn't she doesn't believe him. I don't know what to do. I really want to date this boy, but I don't want to ruin anything.