This is a sad thread. Michael was right in his first post. It all depends on if she signed a release. If she did end of story, she goes away with nothing.
If she didn't sign a release, I would suggest a burning party. I would never give away any negatives, she has no real right to them anyway, she did not pay for them and she was paid prints for the shoot (which she gave to a prior boyfriend). Invite them over and burn them together.
Did you learn something about shooting the nude figure with her? If so then you did gain something no matter how this all ends up.
Now, I hope you see the need for a release. Besides any problems like this that may come up, there are more sticky issues with proving that the model is of legal age. Something very important to do now-a-days just in case some one ever wants to claim someone was underage.
This happened to a friend of mine a few years ago. We had worked with a number of local college students. One called him up after graduation thinking that maybe she didn't want those images of her out there. He laughed on the phone and said to the model, "you had no problem signing the release at the time of the shoot and being paid for your time. Go away." While his comment was a little cold, he was right. Funny thing, I shot the same model and she never called me about wanting any of the work back.
I also recommend ALWAYS having an assistant, wife, girlfriend, or another photographer present during a shooting session. We don't need any models leaving your shoot and then claiming you attacked them or something. Try proving you didn't, much easier to have an assistant there.