Stop contacting this girl. If she wants to talk, let HER call you.

When she does call, (and she will) don't be an ass but DO be apathetic.

If she flirts with you, ignore it. Sooner or later she's gonna snap and she'll practically be begging you to fuck her.

Yes, I know, It sounds like an asshole move. But it works.

She freaked out on you because you where acting all desperate and clingy. Show her you're not that guy and your in.