She must be obsessed with him!

I just started out in college, and some of my girl classmate started hating me for no good reason at all!
She taught that the guy she likes is courting me. She even threatened me that if she found out that we were together she will like kill me!
And that's not just it! She bullies me and started spreading bad and untrue rumors about me!
I was really mortified and shocked! I don't even speak to her crush! And I don't even give a damn about him!
I don't know what's wrong with her! She's obsessed with him! But why is she threatening and making me look bad to other people?
what's wrong with her? I try to control my nerves but I might sopner lose my patience! aaarggh. she's nasty!><