I want to get over him but im not sure?

ok well i have a had the biggest crush on this guy i nicknamed him blue since February, he's 15 my age, but he has a girlfriend who is three years younger then him, I really like him but i don't want to tare them apart i know he's happy and i accept that so i decided to wait for him, but today my friend told me that blue said he doesn't like me and never has so he probably never will (by the way the friend i just mentioned is my ex) I want to believe him and at the same time don't so i don't know what to do do i get over blue and make sure that he stays happy with the girl he likes or just stand on the side and let him be happy, because i don't want to ruin their relationship so what do i do?