The girl I like is so evil to me

There might be a clue in the way you are online asking total strangers a question we can't possibly know the answer to. What I'm saying is that there's probably a good chance you aren't a good communicator. You have told us nothing about you or her, and yet you want us to tell you why someone is mean to you. So I suggest that you ask her! Have you even revealed to her how you feel about her? Is it possible that she knows you like her but you won't go past that stage? I'm grasping at straws here. Give us some clue.

What have you done to her?

How old are you? Maybe she doen't like you.