It seems like you're asking, "how do I get out of this situation," while you may want to ask yourself, "what am I getting out of this relationship," and whether it is something that's good/healthy/etc. The former is you seeking a short-term "out," which is actually pretty simple--just stop leading her on--whereas the latter is getting deeper into the personal, "who am I, what do I want out of life, and why do I do the things I do," questions that are essential to successfully navigating through our lives and avoiding (or at least preempting) seemingly intractable situations like the one you find yourself in.
There's another person on that line, someone who deserves to be more than just an object to be simultaneously resented and exploited, and while you should have laid-down clear boundaries from the beginning--"I don't want an IRL relationship with you but I'm totally down with cybering"--doing so now, while perhaps painful for her and awkward for you, is by far the more fair and reasonable solution, one that won't continue to demean you both. If you lose-out on your cybering partner, so be it; to tell the truth you fucked it up from the beginning by being self-indulgent, wanting to leverage your sexuality in order to get someone's attention/devotion, and by leading her on in the way you have.
On the other hand, perhaps there was an element of her exploiting you that you enjoyed or needed to experience. You call her a slut, and seem to like treating her like one, but the reality is she could be bullshitting you just as much as you're power-playing her; to make her seem more interesting, or to make you think of her as a sexual being. It seems to have worked, because supposedly you otherwise wouldn't be sexually attracted to her, but now it seems you're addicted to this fantasy the two of you have.
Often when you get into uncomfortable situations you have to ask yourself: how did you let this situation get to this point; what were you really trying to do in the first place; and whether perhaps what you were doing was fair to these real people, or to yourself for that matter. While it may be a natural impulse--especially for people with burgeoning sexuality and perhaps little experience in that realm--to manipulate other people in order to feel sexually empowered, it's overall a pretty crappy thing to do to someone, and can be done in a much more positive fashion in any case (get a real girlfriend whose attention you can respect because you place her on an equal level with yourself).
