How to stop liking her ;( tired of bein f**ked about?

Only time will help. Try your best to cut all contact with her, it will only help. Listen, you sound like a sweet guy and she obviously doesn't deserve you. You're right, she doesn't know what she wants so it's time to move on. You'd be surprised what girls you meet that go to your school; not all of them are like the way that you described. One special girl will come along, trust me on that.