His to Break by Penelope Prince

His Obsession. Her Undoing.
Dr. Aiden Shaw is everything I ever wanted—handsome, smart, rich, and dominant.
There’s one problem. Aiden has an addiction.
And I’m the only doctor who can treat him.
He doesn’t want my help, so we make a deal.
If I fulfill his every desire, Aiden has to open up about his past and bare his darkest secrets to me.
He promised me pain. I promised my body.
I wanted to fix him. He tried to break me.
My submission is the only way to save him.
But our experiment could shatter us both.