Mean Girl- please help me?

Ok, so this girl at my school, lets call her Kelly, is just plain rude. She was a really good friend of mine, up until recently. See, some new girls, lets call them Kim and Cat, just because this is on the internet, moved in, and they are friends with Kelly now. Kelly has always been a bit rude and bratty, but for a long time I was able to put up with it. But now she's starting to be even meaner to my friends. See, she's mad at my friend who hurt a friend of hers, and so Kelly's group is shunning my group because of this one girl. A few days ago, my friend, call her Mel, sat at "Kelly's Table" to visit her friend Annie. Well, Kelly got mad and kept calling Mel a retard and yelling at her for sitting there. Kelly says "Bring Annie to your table!" when she knows that Annie won't leave because she is friends with Jesse, and Jesse won't go either. then Kelly says "Jesse hates you!" which I know is a total lye because Mel and Jesse are actually pretty good friends. I saw a chat that Kelly and Mel had that Mel saved to show me the truth about Kelly, and Kelly blames Mel for ruining the friendship between Kelly and I. I blocked her and deleted her on facebook because of this. Can someone please help me?