Upload & Sell: Off
Have you already done the shoot?
If not, I would probably tell her that, since she has announced that she intended to steal from me, that I decline her business.
If you have, were you planning on giving her hi-res digital files? If she intends on copying your prints, I wouldn't worry too much about it, as the quality will be poor.
No matter what, not someone I would cultivate as a long term customer !