what should I do (friend problem)?

Okay I have a group of friend there about 6 or 7 and there a girl that use to be part of it that i am bffs with and rest use to be anyways they dont like her anymore (long story) so she sits with the fake people that talk about her and she ditches me for them alot but not as much now but she might becoming over for formal tonight but all my other friends are meeting at this one girl house to take a picture and they want me to go. But i not big on ditching but i really want to go but now i dont know wich to pick PLEASE HELP!