Sex File: Should I tell him about my fling?

"The internet throws up options like 'soon-to-be partner again' or 'partner in reconciliation' but they are a bit of a mouthful and, since this letter is about your renewed sexual relationship, 'sex-husband' is a bit more fun."

"If your relationship with your 'sex-husband' is to have any hope of getting to happily ever after, it is crucial that neither of you feels you have to hide how much you grew during your divorce."

My ex-husband and I, who are in our fifties, are in the process of reconciling after our divorce five years ago. 

I had a brief, life-enhancing fling with a younger man in the interim, which seemed to completely reboot my confidence in bed, but my ex has no idea.