Exes, Ohs, and Mistletoe by Cindy Dorminy

Gwen has had it up to her eyeballs with her workaholic husband. She filed for divorce months ago, but he still hasn’t signed the papers. And when he confesses that he hasn’t told his mother about their separation, she backs Russell into a corner, threatening legal action.
But Russell has his reasons. Like the fact he hasn’t told his widowed mother that Gwen wants out. Or that he’s still madly in love with his wife even though he realizes he’s been more dedicated to his work than Gwen these last few years.
After procrastinating as long as humanly possible, Russell reluctantly agrees to sign the papers, but there’s a catch. A big one. Gwen must pretend to still be in love with him while they spend the holidays with his mother in Holly Grove, Vermont. And maybe, just maybe, this sweet small town with its Christmas magic might ignite an old flame, and give their teenage daughter the Christmas present of a lifetime.
Exes, Ohs, and Mistletoe is a standalone novella as well as part of Let It Snow: A Holly Grove Anthology.