Why is this girl switching the story around?

[ace]

Had you ever denied a girl who asked you to be more than friends then later have her try to make it appear the other way around? Well that is what happened to me, and this psycho is starting to really creep me out. After denying her, I didn't talk to her really ever again. I told some friends of mine who asked what happened, so I told them. After that, I've been getting long stares from her, when I approached her one day to be nice (two years after turning her down), she acted very friendly, then I get a threat message online from her to leave her alone that she'll contact school security. So I did. Well one day (try 2 months later) I mistaken her for someone else and approached her. She was rude, so I got pissed and followed her and demanded an answer for her cocky attitude and she talked to me as though she was the one who was doing the denying and when I brought up the truth, she said that never happened stormed off, went to the bathrooms and cried. She saw me going to the school security building a few minutes later, and she went there too to make a damn show. Well later I talked to the dean of students, which in turn talked to her, and we made a verbal agreement to leave each other alone. Well, after that, she's been kind of stalking me on the roads for I see her several times a day now ( maybe once a week in the past), so it has increased by a lot. She still does the stareing but it takes place out of the school, and I don't have really any evidence to take her into court to get a silly restraining order, plus it costs money (the court is usually on the woman's side too). But my main question is, why does she try to switch the story around like if it was her the one that did the denying when she knows what's happened, so why is she lying to herself and to me? Plus I outnumber her in friends and they all know what happened too. So why is she fooling herself?