The only thing I can think of is being repulsive to her. She will definitely leave you alone if she thinks you're the grossest person ever. Lol. That might be difficult or not depending on how far you'll willing to go.
After reading several of your replies, that girl sounds crazy and obsessive. Why not file for a restraining order? Does she appear to be dangerous at all? I would be freaked out.
Tell her you need some "me time" and that you'll call her when you want to get together with her. Then don't call.
Well for an emergency OK but for socializing you need to be honest, don't think you're going to be able to get around hurting her to some degree.
Might work, but then again it might make her jealous and try harder
Tell her you are entering witness protection.
introduce me to her as your friend
well then obviously she didn't see me, my appearance never fails to scare off anyone
Stop bathing or brushing your teeth.
oooo that's scary. Good luck!
How old is she?
Ask her to pay for dinner from now on. Also, refuse tongo to work and/or wear pants.