Dark Side of the Sun by Addison Cain

Arabella, the Baroness of Iliffe, knows her life is nearing its end. For years the young widow has been hunted across England, running from her past, thrust onward into desolate wastes until there is nowhere else to hide. With the little time she has left, her desperation has driven her into the arms of an extremely sinister man who desires more than just her company.

Gregory Harrow, bastard born gentleman, takes what he wants, and is willing to use anyone and anything to achieve his aims. Greedy, cunning, cruel, he claims to love her, offers to kill for her, but lies come easily to his tongue.
She knows she cannot trust him, but making a deal with the devil might just be her only chance for survival.