I looking for book about a woman who dream about being lover to medieval king

I read a book a few years ago.

It was about a woman who started having dreams about being a slave to lover to assassin to medieval king.

She also started to not tell the difference between present life and past life.

Can someone help find this book?

You might want to try posting over at Name that Book.

Sounds like "Lady of Hay" but that is about a noblewoman and her fight with King John. You might like that one.