ahh! real big realtionship help-please!?

Ok so here's the story: me and this guy had been dating for a while and we were like best friends. after we broke up we continued to be really close friends and we always kinda had a thing for each other. we told each other that we'd go out eventually again during the school year. well then we sort of branched our seperate ways; i began seeing someone else..and he did too. after a while i broke up with my boyfriend, and now im feeling kinda lonely. i want the first guy back--but how and what do i do? he has a girlfriend, but i feel like we'll always have that connection. and how would i know if he still has feelings for me? ahh please help.