My friend's friend is bad news.?

My friend Kellie is really sweet and recently she kinda ditched me and began hanging with maria. At first Maria was mean and purposely tried excluding me and my other friends from Kellie, but she is a little better now. She is very outgoing and funny, but sometimes still sy. But the bad part is, he old best friend even told me she really only hangs out and is best friends with one person who is in her homeroom and ditches them the next year. Its so true, Ive noticed the pattern. I tried to talk to her in person and over facebook, and she called my a cyberbully and a liar. Our relationship is fair now like aquantince level, but i want it back to normal