Why Cant I Get Over Him?

ok so i was with this guy for a while and we broke up i was crying and he tried talking to me but i ignored him after a while ever time i see him i get all nervous i still have feeling for him and my friends tell me to get over him but i cant tried to but i couldn't i don't like any one else and sometime he will stare at me and i start getting nervous again ... please how do i get over ?