Undoing One's Enemy — Camille Oster

Lord Eldridge returns to London to reclaim the estate that had been stolen from him. He is determined on the ruination of the family that destroyed his, but his plans conflict with his gentlemanly duties to the remnants of the Hessworth family--Amelia Hessworth and her ailing aunt.

Amelia Hessworth's willful pride and determination only increases the stakes as she refuses to accept a fate less than the one she wants. She won't let circumstance or the arrogant man who's come to throw her out of her home stop her, even as she has little choice in the short term but to rely on support from the man who despises her. In fact, she learns to embrace the freedom outside of Society's strict expectations.

To say they don't get on is an understatement, but circumstances can be cruel.