Mabel 1 by Erin R Flynn

Mabel Matthias agreed to be married off to benefit her family because it was the duty of a noble daughter. Raised as a doll to be obedient and do exactly what the men of her family, and later her husband, tell her, she endures the humiliation of her husband already having a mistress who lives in their house.
And it only gets worse from there.
After six years of torture at the hands of her husband, his mistress, and the house’s staff, her husband demands for her to sign divorce papers. As excited as she is at the prospect of being freed from that monster, she has to speak to her father first.
But instead of a man concerned that his daughter comes home abused and scarred, he demands she go back and fix her marriage or kill herself instead of embarrassing the family with a divorce. Her brothers make it worse by jeering at her after all she has suffered to improve their lives.
No more. No more will she allow herself to be treated this way by monsters who have no love for her and abuse her.
Grand Duke Ian Brooker sees the sister he cannot save when he looks at his enemy’s wife even as her beauty captivates him. Commander Andre Lessa is ready to give up on his position and his hopes for the future when he encounters the most surprising woman who is fighting to keep going and he can’t seem to stop thinking about her.
But will either be able to help her, or will their history get in the way of what is best for Mabel?