I don't know of this helps...But any picture you take is your copywright. She has stolen your propery and reproduced it without your permission. That is copywright Infrigement in the UK.
That is a legal matter, look into it... you could just mention in passing that you have had a lawyer looking into that particular subject....
Just plant the seed, she may go away of her own accord?
My dad is a photographer, and he has had this happen, and thats what he did...seemed to work for him. Although he never got any true retribution, he never saw the theif again.
Pictures were safe...
good luck