Reforming the Duke by Keira Montclair

This book was previously released as The Duke and the Dressmaker.
The last woman he should want. The only woman capable of healing his heart.
After his divorce, Philip St. James, the Sixth Duke of Brentwood, is once again a sought-after bachelor. Unfortunately for the ladies of the ton, he has vowed never to remarry. His ex-wife broke his heart, and he will not risk opening it to anyone new. But when he meets Lady Sara Downey, the jilted wife of the man who broke up his marriage, he is shocked by his powerful attraction to her.
Romance is the last thing on Lady Downey’s mind. After her husband abandoned her, she used her secret inheritance to open a dress shop. She loves the work, although it has lowered her status in the ton, making her all but untouchable. Which is why she fails to understand the Duke of Brentwood’s sudden interest in her. Dashing and handsome, he is everything a man should be—but the last thing she needs is a suitor, and everyone knows a duke would only want one thing from a dressmaker.
When a vicious blackmailer attacks Lady Downey, the duke is determined to help her. The more they are thrown together, the more their connection blossoms, but will the wicked man tormenting her rob them of their second chance?