If you do decide to expose their affair, it needn't be (and shouldn't be) to anyone whose business it isn't ANYWAY. The idea of confrontation and exposure is to expose the affair to the OM/OW's spouse (who deserves to know), and to just a few key influencers in the wayward spouse's life -- parents, siblings, adult children, maybe a best friend. To do more than that does get into vindictiveness, and "airing of dirty laundry," and can cause problems once the marriage is healing.
There are two distinct schools of thought on exposure (I happen to be a big proponent), but I didn't want to leave the misconception out there that this is something that's done to the hoardes.
Regardless of what you decide, as someone else said above, do NOT let him continue to cake-eat. He will lose all respect for you, and you for yourself.
