His Southern Belle by Annabelle Marin

After the Civil War ends, Charlotte Louise Prescott finds herself struggling to survive. She has no money, and she is desperately trying to hold on to her once grand home.

John Parkington thinks he gets the luck of the draw when he stumbles across an abandoned plantation. What he doesn't expect is a little southern belle trying to stab him in the middle of the night. John works out a deal with Charlotte; he will allow her to stay, and he'll help her rebuild the plantation. The minute she leaves or marries, she forfeits her part. There is no way Charlotte will give this man her family home even if he can't keep his hands off her.