OMG! The same thing happened to me a few weeks ago. She was my best friend in the grade. Now at lunch I have no one to hang out with, and when we have projects we get to pick a partner. But I had no one for a while. Then I saw these 2 girls, and I started hanging out with them. I told them my story about me and my friend. They understood, and all the other girls started hanging out with us, except her. Maybe you should do the same thing, just a suggestion.