Velvet Is the Night — Elizabeth Thornton

To save her family from the guillotine, a young beauty becomes the mistress of a ruthless commissioner--only to find herself falling in love with him.. .

SHE SWORE SHE'D NEVER LOVE HIM
He was cold, ruthless, evil... and as the newly appointed commissioner, Phillipe Dubet had the power of life and death over the local aristocracy. In return for her family's safe passage out of the country, the breathtakingly lovely Claire Devereux agreed to be his mistress. She was to live in his luxurious quarters, to be seen with him about town, and to accommodate his desires whenever be wished... Claire surrendered her body to Dubet, but swore he'd never break her spirit. What she didn't know was that the real Dubet had been abducted, and his American twin brother Adam Dillon installed in his place as a spy. And she was devastated to find that her body was not at all immune to the pleasures of "Dubet's" caress, nor her heart to his intoxicating company.