My bestfriend is changing should i forget her?

well im in gr 8 now but i met lisa in grade 7 and ever scince then we have been close friends ( besties) so in gr 7 there were these populares we were great friends with them they were kind but we didnt want to be in their "groupie" we just wanted to be friends with them me and her were great but i felt like she chose people against me for example there was a test and she let others ( populares)cheat from her ( she was smart) but not me , ( i get nervouse when i do tests i stuuddy and forget everything i have a phobia) and it hurts my feelings also she has another bestfriend who i met shes cool but i feel like she chooses her over me.. =/ anyways this year i moved out of the country and we talk on fb and i feel like she changed i know its rong but i went on her fb and she is becoming one of thoes populares and she hated jb but now just cuz they like him she does shes like " IM OBSESSED WITH HIM" like shes such a wanna be now and idk i just dont wana be around that anymore i honestly wanna forget her.. =/ should i?