Need help! i dont know what to do!!!!! big guy trouble!?

hi, when i was 13 i went out with this guy for 2 weeks and back then i thought i was totally smitten but after we split up like most 13 year olds i moved on pretty quickly but this guy has always been in the back of my mind! recently i have got back into contact with him (im now 18) and we have been flirting, meeting up etc and he made his feelings clear that he liked me and i like him too, now wheres the problem here it is.....he told me that he wasnt sure i liked him so he now with another girl and doesnt know what to do, he said bout me being his secret but i said no! but i feel like im falling fro him big time! he keeps saying that he really likes me but doesnt want to dump this other girl cus it not fair on her! what can i do? i really want to be with him i cant get him off my mind!