While I understand your husband's feelings vis-a-vis wishing he'd never learned of your affair, it's flawed thinking. The fact is that, whether he knew or not, your marriage was severely compromised while you were in your affair. He may not have known, but his life hung in the balance. Not knowing doesn't change that. And it doesn't change the need to address the problems. Take it from someone who was in the dark for a decade and a half--who could never quite pinpoint just what was so wrong with ME that our marriage did not work. (Really? There was nothing other than a wall constructed of secrets and lies erected by my WH.)
Your friends' marriage is already hemorrhaging, whether the BH is conscious of this or not.
So, telling the other BS is, IMO critical. You know---how could you keep it secret?
What good will confronting OM do? None--he's cheating with a married woman. He's not a friend. He's dangerous to both marriages.
And the other BS deserves to know this.
I know it's easy to say, "I wish I'd never found out." But really, what that means is, "I wish to God my spouse had never cheated on me."
You can't give that to them.
Nor is letting the cuckolded man---who's currently thinking of OM as a good friend!--know the reality of his friendship and marriage "destroying a marriage and a family."
Your "best friend" and your husband's "good friend" have already done that.
Whether the BS knows or not.
The difference you can make is to gently offer the BS the dignity of making his OWN choices about what is in his best interest, rather than participating in making the WRONG choice for him.
Keeping quiet? IMO, that makes you complicit. I don't always feel this way, but because you are "friends" with these cheaters, if you choose NOT to tell the BS, you are choosing to implicitly support the affair. Even if your husband gives the OM a (futile) talking-to.
Is your fear of hurting the BS? He's already hurt. That damage has been done. He deserves the chance to determine how to proceed.
Or, is your fear of hurting your friendships? Again, the two cheaters have done that already. Frankly, I would go NC with them. Knowing the devastation of infidelity, they have chosen to embroil you in their own---and that makes them friendship material about as much as dressing up like a clown made John Wayne Gacy a good companion for little boys.
(I would not be okay with my husband going on a hiking trip with the OM and his friend. Why? Because he's a BS, and secret-keeping will cause HIM harm. I would not want my healing BS exposed to a weekend-long trigger, feeling responsible for others' well-being. BSs spend FAR too much time in that shitty position already. It's time for some big decisions, FAST.)
[This message edited by solus sto at 7:34 AM, October 9th (Wednesday)]