Keep your friends close but your emenies closer!?

My best friend and I are like unsepratable but about a week ago she become closer with the '*****' of the group. Before my and my best friend will ***** our about and now she don't even speak to me about anything but a hi and bye. She walks to cles lunch recess with each other and I dont know whats up! When I ask my best friend why she hell loves her she says its just a act but you can tell it not. I know they say keep your friends close but keep your emenies closer but help I wanna be as close to her as before.