"Lilith," by J.R. Salamanca.
I've read this twice and love it.
Here's the link to Amazon:
http://www.amazon.com/Lilith-J-R-Sal...lamanca+kindle
Unfortunately, the reviews (how many?) have the Salamanca title mixed in with the George MacDonald fantasy of the same name.
Be aware that the Salamanca title is concerned with mature themes, and may not be appropriate if you are an impressionable teenager.