My two cents:
Ignore her. If she texts you, don't text back (or text back late at night going "Oh, didn't see this before now" (DON'T answer her text!!)). If you are available and, as you say, supplicating she wont be interested. Ignore her, and she will be all like "Hey wait, what? How come he's stopped talking to me? What did I do wrong? Am I not attractive anymore? Has he found someone else? I've got to get him back!"
Ignore her, leave her be for a week or two, then suddenly out of the blue send her a (nice) text message. Then ignore her again. Cat-string theory in the works
That said, if I was you, I'd forget about her and move on. Stop obsessing over one girl, there are plenty more fish in the sea.