C.K.
As a professional photographer I am sorry this happened to you. She should have worked better with you. It was 10 prints, her cost is not that high! As far as photoshop to try to get her water mark off, it is illegal and she could actually sue YOU. By putting her watermark on them, she copyrighted them. I know this is a mean answer, but it is the truth.
If I were you, I would keep calling her until she finally wanted to get you off her back and gave you the prints you paid for.
Good luck.