Send her an anonymous letter telling her to read this very article in Salon. Be discreet, brief, yet firm about it, but don't include any information about yourself. No detailed past history with husband. No return address, no ph. #, no email address. Just drop a subtle hint. If she's smart & curious enough, she'll read it. With any intuition, she'll (hopefully) get the gist. If not, then you'll realize that she's either simply too clueless or blind to put 2 & 2 together, & it will no longer be your problem. You will rest assured that you have done your part.

Then move on with your life as fast as you can.

I was 25, married for two years to my college sweetheart, my first true love. I found out he was cheating when I took a half day off from work to surprise him and join him at the beach for the day, only to find him in our usual spot making out with an 18-year-old girl. It was horrible.

To add to my misery, it turned out that his friends and his brothers all knew he was cheating, which meant that I was socializing regularly with dozens of people who knew what was going on. So I had to deal with massive embarrassment on top of everything else.

I divorced him. In hindsight, the signs were obvious, but the puzzle pieces didn't make a picture for me until I saw it completely formed on the beach.

I so wish that one of the dozens of people who knew had told me. I could have left sooner, with more dignity. I could have done it on my terms, rather than participating in that ugly scene on the beach.

You need to get out (which you already know), you need to tell his wife (which you also already know), and you need your girlfriends to help you with this situation. Tell them you found out he's married. Tell them you hung on for too long after finding out and you hope they'll forgive your lapse in judgment. Tell them you have broken up with him (do it first!). Ask them for their help in telling his wife.

I'm trying to think through how you should tell his wife. In my case, the in-person conversation would have been with one of the many friends who knew but didn't tell. I could have handled that. I pretty sure I wouldn't have wanted to participate in a conversation with the 18-year-old girl. Actually, I know for sure that would have been too awful. She was smug and gloating. I know you wouldn't be that way, but I can't imagine a demeanor that would be suitable.

So I think it would be better to write a letter. Make it honest, make it short, and give her your phone number in case she wants to call. If she does, be kind. She might say awful things to you and about you, and it's your job to listen without getting angry with her. You'll need to apologize a lot, again without getting angry. It would be wonderful if one of your girlfriends could be sitting next to you while you have this awful conversation.

Good luck dear. I sense that you're a nice person who got caught in a situation that you didn't anticipate. You're trying to do the right thing, and that's good.

I'm with Cary. Normally in these type cases I think "stay out of it" but it sounds like here she could actually benefit from being told. But like Cary says, don't do that to her at work. And make sure you don't savor the drama. Make it short and sweet, and then get the hell out of her life. You have a chance here to finally do the right thing. Doing the right thing feels good. It isn't as immediately gratifying as getting embroiled in a huge drama with your hot ex-lover who hurt you so badly and his wife and his lies, but in the months and years to come, you'll feel so much better about the whole thing if you use this opportunity to show some class.

no question. tell her.

these types of guys are too common, and they've snowed too many kind hearted women.

she'll get over it quick enough.

Something I read years ago, I searched it out to paste here, it seemed to fit your situation -

"To repent means "to change one's mind." In and of itself, repentance does not mean to overcome something you did wrong and make it history. Repentance refers specifically to the change of heart and mind that is necessary for a real change of behavior to take place.

While offenders cannot unspill the milk, they can help clean up the mess they have made. They can admit their wrong and then offer evidence that their repentance is real. When we hurt others, we can admit our wrong, and do what we can to make restitution. We can help those we've hurt by assuring them that we had no excuse for what we did.

While it is impossible at times to know whether repentance is real, we can look for evidence. We can expect a truly repentant person to confess the wrong, offer no excuses for his wrongdoing, humbly plead for mercy, and quietly accept the consequences."

~~~~~

Yes, Repentance is a very biblical word, and the publication I have copied from is in fact a very religious booklet, I edited the quote above to take out the god/jesus stuff, it's too easy to be distracted and put-off by the religious aspect and miss the message. I'm very much not a christian, vocal about not being a christian in fact, but still the booklet here:

When Forgiveness Seems Impossible:

http://rbc.gospelcom.net/ds/cb941/

has some really good stuff... I highly recommend it for anyone having trouble with forgiving someone, or having trouble with asking someone for forgiveness...

For years and years Dear Abby and Ann Landers have been giving the opposite answer to this question -- various versions of "not your job, not your business, not your responsibility." Of course she should tell the wife. Part of your final advice to "walk away", however, also means to walk away from the wife; deliver the information but don't stick around to find out what she does with it, have no expectations about what she will do with it, and most especially find a way to feel no frustration or bitterness if she stands by him, calls you a liar or blames you for the affair, and does nothing to change the situation. What she does with the information is truly none of your business and not your responsibility.