Boy troubles... HELP?!?

I really like this guy, but hes popular, and has a girlfriend. i really really want to tell someone, but i cant. Im afraid if i tell someone, someone else will hear and theyll tell him and itll all go bad. I only know one friend i kno for sure i can trust and -maybe- help me. But im not sure if i should tell her. do u think i should?? PLEASE HELP IF YOU CAN!!!!!!