Should i just give up?

ive had this thing for my homies sister for a few years i thought she liked me bc she used to flirt but when i tried to talk to her on facebook after not seeing eachother for a while she ignored me but anyway now she has a bf and i have a gf(who im not happy with) and a child but i still have this major thing for this girl idk y but its like an imprint i cant shake the massive feeling i have for her its not fair to the girl im with i kno but its not my fault i guess i would just pick her over anyone and i feel like wed be a perfect match but in reality wishing for that is not enough n the odds are very much against what i want i love my gf now and we have a child but im just not happy anymore and my heart isnt where it should be. Im focused on my child but not the relationship anymore but It seems like me n the girl will never be so honestly should i keep hoping that someday shel love me back or should just accept that shes not gonna magically text me and want us to be