Photographer's Rights Question.

I paid a woman a sum of money to let me take nude photo's of her.
I have written consent to post them on adult sites providing her face is not shown.
I have a receipt for the monies I paid her.
During the shoot we had a couple of drinks.
She got a little over excited and worked herself up into a frenzy.
I'm a red blooded male.
We had sex and we both took photos of us during the act.
Our faces are clearly visible in some of the photos.
She took a copy of the pictures with her on a flash drive when she left the following morning.
She has told me that she has lost the flash drive and is now demanding I do not post them and wants a guarantee that I will delete them.
If I do not comply she is going to the authorities.
I will NOT post them. I would expect the same courtesy for my request.
I do not want to delete them.
She's getting very abusive because I will not delete them.
Where do I stand?