"New" Bestfriend

My bestfriend since i was 4 or 5 has found a "new" bestfriend it F*uckin gets on my nerves she acts like she doesnt even care she spends more time with her "new" bestfriend then me. I havent told her because she cant see what she is doing and will deny it. She met the girl this year in school! It f**kin sucks i want my friend back but not tare there relationship apart! >:|