I wish I had never met her

Hiya, there's this girl who, up until now I considered a friend. I now realise she was just using me all along. She makes my life a complete misery. I wish that she had never moved to my school in year 3, I wish she had gone to a different secondary school to me, I wish she had transferred sixth forms. But no, she's still here. We hang out in the same group but she is UNBELIEVABLY rude to me, saying 'no one cares' if I talking and constantly having digs at me. Calling me weird, questioning my vegetarianism, reminding me that I'm friendless ect. If someone is teasing me she will side with them and join in. After all of this, she will come crawling back to me, acting as if we're besties. I bet you in a couple of weeks when she's bored of her other friends, she will come crawling back. See, she was supposed to be a friend, and she would be rude and act in a mood with me completely out of the blue, especially infront of other people. She's been like this since year 3. I really want to yell at her but I haven't had the opportunity yet. I don't know what to do.