I'm going to get angry at a girl who tried to tell a new student to not speak to me because I'm annoying
Why would you get angry at this girl for talking with the new student?
Because I believe it is perfectly reasonable for someone to decide to speak to whomever they want to speak to
If this girl wants to bad mouth you to a new student, getting angry with her over this trivial exchange is a waste of energy. Let her say what she wants and go on with your relationship to the new student anyway.
Fuck you. You are stupid. What are you bad mouthing me for? Why do you say I'm wrong anyway?
I'm not saying you're wrong, I'm saying you're overreacting. What I'm saying is, the student will see the girl for who she is. Getting super defensive will cast you in a good light.