Everyone, thanks so much for your thoughtful advice. I've been in a sea of emotion shifting back and forth and being torn apart. It's good to hear from people who want to help and have some perspective.
The marriage and family counselor who recommended AM (I'll call her MCGF) is really the motivation for me posting here on SI. WW and I were gradually coming together after DD#2 (April). She answered my questions for the most part, though didn't volunteer much or help me much in my inquiry. But it was something. We had some hysterical bonding which was fun, and it looked to me like we might have a chance.
About 10 days ago we were talking and I asked her "Why won't you tell me the name of MCGF? I don't even know her, what's the problem?" I was thinking I'd like to look at MCGF's web site and see if there was any weird new age psychological principles she advocated. I also had a strong need to know the name so I understood the story of the affair well enough to heal.
WW said that the conversation was in confidence and didn't want to "betray" MCGF by revealing private conversation. She said that MCGF was just a friend and they'd had a few drinks and it wasn't MCGF's fault anyway. So I got upset and said it was a bad decision not to tell me, and that it drove a separation between us and it was hard to understand her priorities.
She then said the words that will ring in my mind, maybe forever:
"I will not tell you the name, and if that ends the marriage, I'll be sad."
I was shocked. I said, "It just might" and walked off.
About an hour later I came home. She asked if I would keep the name a secret and I said yes. She told me.
It was the name of a friend. I know her, and I know the husband. I've coached her kids.
So another lie exposed (she told me that I didn't know this person intentionally to keep me from figuring out who she is.) Another betrayal (MCGF knows me and should have foreseen what this would do to me.)
WW created another threat to destroy the marriage instead of meeting my need to know what happened.
But wait, it gets worse. Over the next few days I noticed that I had said several times that what MCGF did was "wrong" and it was my right to blame MCGF for that. I noticed that WW kept defending her by saying the A was her own decision (true enough) and that what MC did was "gray" (not true for anyone who expects to be married to me) and she blamed me for black and white thinking.
I was so upset. I asked her, "Would it be 'wrong' for me to recommend AM to our DS after he got married in case his marriage got in trouble?" She said it would be "inappropriate." She couldn't bring herself to say it was "wrong." It was as if she's swimming in a sea of gray where nothing is right and wrong.
Only later did she finally admit to me that these things are in fact "wrong" but kept saying how upset she was that I pressed the issue so hard without allowing her to retreat and wait for our (real) MC to intervene. She kept saying that she was upset and felt pinned down and that she can't think in times like that (so I guess I'm supposed to give her a pass for whatever BS she says in times like that?)
Up to that point I'd wanted to be close to WW. I wanted to touch her and talk to her and have sex and all that. I've been nervous that she'd regress, and of course there wasn't much trust there.
But now I feel numb and can barely stand to look at her. I feel totally out of love. It's like I'm starting a 180 but not on purpose, it's just natural. I took my ring off a few days ago, can't stand to wear it. I'm thinking about life alone and coming to accept what that might look like. I look around our beautiful house and look at our fantastic children but I can't visualize holding it together.
All this started because she wouldn't tell me what MCGF did was "wrong."