Another vote for stay out of this.
I would say that’s roughly analogous to receiving a letter from an African Prince who needs your help getting $30 million dollars out of the country and accepting his word that he needs $3000 as an “expediting fee”
I don’t think it’s really a matter of blaming the victim or not. If the cheated on spouse is in denial about the cheating for a while, it doesn’t make the cheater any more or less culpable.
The only thing I think should be done is for Dan to explain to Jack very clearly that Dan can not be his confidante - that the conflict of interest between his role as Jack’s friend and as Jack’s son’s stepfather is too great for this type of situation. I think this would send the right messages to Jack - that his actions are NOT approved of by Dan, and that his actions have far-reaching detrimental effects to Jack’s family and friends - without causing upheaval in the son’s family by telling Cathy.
Isn’t your business. Stay out of it.
Seconded.
I think we have a winner.
The only dog in the fight that your friend “Anne” has here is that her husband has compromised his own promise to a friend of his not to tell anyone else about the affair, and told HER because she’s his wife. Presumably there was an implied, if not explicit request that she not propagate the matter further.
She has already violated that by telling YOU. Mistake #1.
The fact that she is contemplating sending “Cathy” an anonymous note on the subject (and I assume that other than being the wife of a friend of “Cathy’s” husband, “Anne” has no direct relationship with “Cathy”) is an even bigger (and somewhat incomprehensible to me) mistake.
There is literally no upside to such an action for her (“Anne”). If her husband finds out she’s spreading the word, it’s as good as breaking a promise or lying to her husband – he will not think she can be trusted with a secret. Many husbands/wives implicitly share all secrets, if that’s the case, then there is an implicit “mi secreta es su secreta” understanding as well.
Who’s Cathy to Anne, or Anne to Cathy, that she should weep for her so?
(This is getting a little weird for me because two of my sisters-in-law are named Cathy and Anne, fortunately neither is married to a Jack or a Dan…)
I’ll temper my earlier reply after re-reading the OP – I can see now that “Anne”, by dint of keeping on a good relationship with her ex-husband “Jack”, apparently does personally know (and on reasonably good terms) Jack’s present wife “Cathy”.
I would say Anne is in her rights to call Jack out on it and encourage him to come clean to Cathy. It shouldn’t shock Jack that Dan has told his wife, Anne, even if Anne is Jack’s ex-wife. But she should not bring it up with Cathy herself. (Save that for blackmail if things blow up between Jack and Cathy, resulting in Jack moving away, and suddenly seeking custody of his child with Anne.)
Disclaimer: this is the sort of thing I would do (and have done) in very similar situations. It didn’t always lead to what I would consider an ideal outcome, but it always left me with a clean conscience and no need to try to force a confrontation between significant others.
“Jack, 5 people that I know of know that you cheated on your wife. All of them know your wife, and all of them like her. None of them, to my knowledge, are at all happy about the situation they’re in right now - where, presumably, they know and she doesn’t. What you do with this information is up to you, but I think you should be aware, in very clear terms, of how quickly this information has spread, and how you’d like Cathy to hear about what happened.” Usually this leads to the cheater putting their spin-machine on High, but at least the facts come out in the open without someone who isn’t in the relationship having to inform one of the people in the relationship about their partner’s infidelity.
I don’t know why people always say MYOB to this kind of stuff. I couldn’t disagree more. What if he gives her AIDS. She needs to know she’s not in a monogomous relationship. nI don’t understand why people are always so eager to protect cheating slime balls. I’m a big advocate of narking them out.
I agree. I hate being put in this position. It makes me an accomplice and makes me feel like I’m violating the trust of the cheatee. There’s nothing more uncomfortable than sitting with a couple and trying to act like everything’s fine and dandy when I know it isn’t. It makes me feel like a heel.
As soon as I’m made an accomplice, that makes it my business. Just think how you would feel if you found out one of your friends had helped to hide your spouse’s infidelity from you.
Because too often its a defensive block that misses and you just end up hitting yourself in the face. The spouse knows and doesn’t care - and now thinks you are a busybody. Or they don’t know, but they don’t believe you - and now you are just a hateful jealous gossip. Or they don’t know, they believe you, but they would have rather not known and blame you for ruining their happiness. Few people are grateful for “oh, by the way, that husband you love and trust - he’s boinking Julie.”
Having been the cheated on spouse (who sort of knew), I’d want people who are close friends of mine to tell me - not because I didn’t know, but because I needed to hear I was worth more than that and I should dump his ass. But I sure as hell wouldn’t have taken it well from my husband’s ex wife (he didn’t have one - how about any of his ex girlfriends) regardless of how friendly we were.
As mentioned upthread, the chances of her giving his wife AIDS (HIV) are practically zero, and they are similarity slim odds for any major STD. The other point is that not every person who cheats on their spouse is a slime ball. More generally, getting involve in other people’s business is not advisable, especially when there would be considerable damage done all the parties involved. The damage that would be done to the child is enough reason to avoid getting involved.
Yes, Cathy and Anne get along really well, as do Jack and Dan (obviously). It’s rather strange sometimes, like being in Bizarro Divorce World where the new wife invites the ex-wife to her baby shower, and the ex-wife will babysit the new wife’s son.
Maybe they’re all just a wee bit TOO friendly with their exes. 
I think in a situation like this you need to consider things from a Buddhist perspective of doing no harm - what action of yours causes the least harm? Although frankly, I would hate being put in the position of knowing something as potentially life-changing (in a bad way) as someone cheating on his spouse and not telling them.
Not to mention that it’s so obviously a poorly disguised excuse for moving The Drama to the next level. Neither of these women have any knowledge of anything except gossip. You don’t repeat gossip to people when you can do this much damage.
So in other words, Anne should tell five people, and then use the fact that five people know to mess with her ex-husband’s marriage.
Generally, I don’t think it’s about protecting the cheating slime balls. It’s about prioritizing. In my mind, Anne’s responsibility in this situation is to the following people, in approximate order of priority:
(1) Her child with Jack.
(2) Herself
(3) Dan
(4) Cathy / Jack
Telling Cathy would be viscerally satisfying, of course, but it would be harmful to persons 1-3.
I mean, here’s a thought experiment. You’re married, right? Suppose your wife had a previous marriage and a child derived from it. Suppose one day her former husband, with whom she is unusually close given their divorced status, came to you and said, “Diogenes, your wife is cheating on you.” The first thing you’d do, give or take, is go ask your wife - are you cheating on me?
Now she says “No.” What do you do? Do you automatically believe her former spouse, over your own current spouse? Very likely not. Particularly not since her former spouse could have any number of motives for lying about this. Maybe you choose to believe your wife, and for the rest of your days think of her former spouse as a liar.
The same is the case here. If Anne tells Cathy that Dan told Anne that Jack told Dan that Jack was cheating on Cathy, the benefit that will accrue from that - such as it is - accrues to Cathy (and, I guess, Anne gets the satisfaction of outing her ex as a cheater). But it accrues only if Cathy believes Anne, which she very well may not. Meanwhile, the downsides will hit Anne no matter what. The resulting rancor between Anne and Jack will affect their child. If Cathy doesn’t believe Anne, there will be additional rancor between Cathy and Anne, which will also affect the child involved. Dan gets hurt, because his friend Jack will be pissed at him. Anne gets hurt, because her husband Dan will feel that she betrayed a confidence and trust her less. Based on the priority list above, telling is exactly the opposite of what’s best for Anne.
Huh? Four of the five people are Jack, his unnamed paramour, Dan, and Anne. What are you talking about?
Wrong. Read A Priori Tea’s post again.