Not that there's anything sexy or legal about teacher/student relations (abuse if a minor), but it hasn't stopped some novelists from writing about the matter. Here are a few that broach the subject. I'm sure there are many others.
Boy Toy by Barry Lyga chronicles an 18-year-old baseball player and math major who has flashes of an ongoing affair while in middle school with a teacher at the school. There was a brief note of the book in this weekend's L.A. Times book review section. It's gotten good reviews.
Last year's Academy Award nominated film, Notes on a Scandal, was based on a book by Zoe Heller called What Was She Thinking? Notes on a Scandal. The story follows an ongoing flirtation between a young teacher and a high school sophomore that soon becomes more than glances across the school yard. I loved the film. But the book... excellent! Loved the writing... and some great one-liners.
Over the weekend, I read a short story called The Term Paper Artist by David Leavitt, that follows a college professor who writes papers for cute undergrads (guys) in exchange for relations. It's in his collection of novellas, Arkansas. Great story. Some interesting gay/straight interactions and negotiations.
Again, not an endorsement at all of these types of relationships. Don't want you doing anything that'll get you on Chris Hansen show. And being sexually abused is not to be taken lightly. But there's a saying that if it's happened, someone will write about it. And if it hasn't been written about, then that's your story to write.