This story is about an English guy who's married, goes back to school to get his degree so he can qualify for a promotion at his firm. He finds out his wife is cheating on him with this well-known author, and ends up hooking up with a university student while in school. Later on, he gets back together with his wife and the university student.
Check this one out, it may be it. Lightning Does Strike Twice
https://storiesonline.net/s/46651:39344
Unfortunately that's not the story I was thinking of. He doesn't have any children in the story I was thinking of, where the main character in this one does. Thanks though!
That was the closest hit I got using the search system, ho0wever, I was sure I'd read one like what you're after, so I went digging through my library of tagged stories - maybe Never too Late is the one you want:
https://storiesonline.net/s/69405:i
