This is an interesting fetish, one that does not get the attention one would think on sites like this. It's curious, when one considers the overall popularity of the two acts, that there is an entire category basically devoted to incest while cutting is somehow, even in a place like this, looked at as too taboo.
I have dated a few girls with cutting fetishes and know many more. Your treatment of the subject does it justice, and the writing is well-paced and exciting. I found the story arousing and enjoyable even in its inherent replusiveness, which is pretty much what you want in this sort of tale.
If I could offer criticism, all I would say is that the beginning, where she details the credentials of her perfect life, seems a bit stilted. Not cliche exactly, but formulated. Having said that, some of the description in those sections is very nice. You have the ability to turn a phrase, a neglected and often overlooked talent on this site.
I would love to see something like this expanded into a longer story, where you showcase the struggle and release in alternating scenes of choking repression and forbidden release, ultimately leading to something terrible, something wonderful, somewhere, maybe nowhere. There is an audience for this regardless of the knee-jerk rejection it may inspire in people not intimate with the subject..