Despising the Duke by Stevie Sparks

Sixteen years ago, Lady Annabelle Fraser broke him.
Kit, the Duke of Aylesbourne, has been running from his demons ever since, be it journeying into the heart of the Antarctic or narrowly avoiding death in an avalanche on Mount Everest.
He would have rather faced death than Annabelle.
But when he finds her in bed with one of his old friends, he snaps.
Because sixteen years ago, Annabelle promised to wait for him. And this time he isn’t going to let her escape.

Sixteen years ago, Kit abandoned her when she needed him most.
Some might call her a spinster. Annabelle prefers to think of herself as an independent woman. When Kit discovers her affair, however, he does what she never expected him to do again.
He ruins her.
Disgraced in the eyes of society, if Kit thinks Annabelle is going down without a fight, he’s got another thing coming.