Again...telling OM"s betrayed wife is a personal decision but I would encourage you to do what you inherently likely know is right. No matter how this ends up...yours is the face you will see in the mirror thereafter. Conduct yourself with integrity (and I respect however you want to define that term).
The logistics....
Do not forewarn your wife or you'll just make it that much worse and harder. If you warn them they will use the time to coordinate to thwart your telling by claiming you are a jealous vindictive maybe dangerous abusive husband of some lady OM works with and to ignore you. Also do not do it anonymously. You have nothing to be ashamed of. Give your full name, phone # and email address. Tell the other BS all about the affair, offer to share all evidence with her. Offer to follow up to ensure that contact is truly ended and ask the other BS to do the same. The other BS will be shocked when you tell her, so be sure and give your email address and phone # for follow up questions.
If you decide or are forced to do it in person, then bring someone with you and mind your boundaries. Betrayed wives seem to often take the "while I'll just sleep with my husband's affair partner's husband" as an snap revenge instinct. Be helpful but you are not a counselor and you have enough problems on your own plate to worry about fixing their marriage. Just the facts.
I will pray for you and your family.
The internet is 90% complaining and entitlement and I hate it because I deserve better!
