I like this guy and he likes me but im inexperienced and hes not?

ive liked this guy justin for ages 3 months,. And he has broken up with his girlfriend, jessica time and time again. about 2 months ago we had this moment in the drain and i told him i liked him, but he didn't say he like me. and we've had other like moments along the way, but just now tonight he told me hes has broken up with his GF for the last time, he said his feelings have changed and he just doesn't like her any more. ( About a month and a half ago was Mel's party, an Friend of mine, and Jamie was there too. He said to me , " so who do you like, still me eventually i was like yes, and he was continuously saying why, why , why, he was still going out with jessica. And last Wednesday i go to this cafe thing, and so does he and he was like " so who do u like, same person as last time ( which was him) eventually i said yes, and he said " ar you ever going to act on the way you feel ", i said " you have a girl friend" he said oh k say i did would u ask me out then" everyone came over so i just walked away) anyways, just now on chat, he told me he has broken up with jessica and that he doesn't think if he asked me out i would say yes, i said no i wouldn't not if it hurt jessica. The only problem i have with dating justin is hes done everything with jessica and i haven't done anything like that, and what if he tries to put his hand down my pants or some thing, i mean iv never even made out before and what he tries to with me. i really like him and that would be so emmbaresing if i pushed him away HELP!!