Dragonfly Creek — T.L. Haddix

Book Three in the Firefly Hollow series. 

When Ben Campbell returns home to Hazard, Kentucky after a five-year absence, the last person he's expecting to run into is the girl who broke his heart - the girl who left town and married someone else. He's done his best to move on, but he knows he's only been going through the motions of living. Determined to exorcise Ainsley's ghost, he approaches the young widow with an offer for a steamy liaison to do just that. 

Ainsley Brewer Scott carries a lot of weight on her shoulders, weight that's left deep emotional and physical scars. Her dreams of an everlasting love with Ben were dashed thoroughly, thanks to her malicious and conniving mother. Back in town to wrap up the old woman's estate, Ainsley's world is turned upside down when she sees Ben. And when he propositions her, he lights a match to her temper that flames into a burning attraction just as strong as what they shared years earlier. 

When the truth behind Ainsley's leaving comes out, the long-held secrets shatter the fragile trust they've started to build. She and Ben have to decide to either walk away from each other for the second time or stand together and fight for their future.