As a postscript, if this story struck a chord with you, here are some links to further explore:
This post gives some resources about actual rape victims that find themselves having rape fantasies.
These are forums on the subject of rape fantasy, many with areas for fiction.
This BDSM slave gets off on being taken beyond her limits.
This incredible series of posts is from a woman who claims that rape roleplays were no longer enough for her, and she started rape baiting herself to unsuspecting men.
For fans of Japanese porn, a visual novel (a type of video game) all about giving rape fantasy girls what they want, called "Please Rape Me".
Unfortunately the game doesn't seem to have an English translation, but they did also make a two-episode anime of it. The English fansub is easy to find with a web search, and it's a delightfully fun and light-hearted, even humorous, take on the subject.
Finally, this quote from this Scott Adams blog post seems amazingly relevant:
"Did you know your body can't tell the difference between fear and arousal? The book Influence describes a study showing that people in scary situations will believe they are falling in love. The brain simply creates a story to explain the feelings in the body. And the story is wrong."