Girls Can Be Mean >:l?

Kay there is this girl her name is Danielle she is SOOO spoiled! Before when i did not want to go to her house for a sleep over she did not talk to me for months! And when she did not get to sleep on the floor when i was at her sleep over she had a fit. The worst part is that she is trying to steal my best friend! So what she does is she hangs out with us then she leaves to find someone else. Then she gets into a fight with them and comes back. Now she is trying to flirt with my crushes >:( I just want to scream at her! But i cant or elses she will reck my life. All I know is I dont care. But i need help. What should I do???