Relationship opinions..

So this girl has been messing with me for awhile for no apparent reason. Ive been ignoring her and she gets mad so she gets worse. Its gotten to the point where now she just tried to be up on my boyfriend yesterday. Her arms were wrapped around him and my best friend seen. She yelled saying, “IM TELLING!” He then moved away from her and went to tell my friend he didn’t even want her on him. Then he sat next to his friend Paul. The thing is that he claims he shoved her away but my friend said she didn’t see that. Also, this has happened before. She tried touching his hair and all he did was move his head away. What should I do? Now she wants to fight me for some reason and I don’t want to fight and get it on my record.

P.S told the principle and he won’t do anything.