As Zak sees it, there's a reason that most of the people who frequent infidelity forums are women. For one thing, since oxytocin promotes monogamy, they constitute a majority of the betrayed parties. "People who feel betrayed are very isolated and vulnerable. Women in particular want to reach out to some kind of group. They tend to like to get together and talk it through. They form random groups quite easily. So who do they turn to? Almost anybody."

Among strangers, cheaters and cheatees can find comfort, support, and affirmation. But the woman who confesses her own transgressions can't trust that she'll get a sympathetic hearing. On iVillage a few years back, a flame war broke out when a contingent of women from the Betrayed Spouse Support board began lurking on the My Affair board for clues to their situation—and suspected, based on what they read there, that certain My Affair posters were the actual women cheating with their husbands. This despite the fact that everyone involved was anonymous and that the plot lines of affairs tend— let's face it—to repeat themselves.

But the forums are generally self-regulating, leaving the original poster to pick and choose from a range of reactions. On, one married woman's shame-filled confession of kissing another man generated a score of condemnations ("Your soul will be crushed"), a smattering of "Don't judge yourself so harshly," and, finally, "This is what this site is perfect for, what anonymity is good for. OP has exactly the right take on this—she knows she screwed up, she's not going to complicate her life or hurt anyone by telling anyone IRL. So here she gets to 'talk' about it and make smart choices for herself and her family. Bravo!"

On some sites, there is no way to know who is posting; there are no identifying names, and participants keep their identifying information to a minimum. "There are times when you just want to get a fresh perspective—or ask the crowd," says Justine Reese, senior product manager at "You can throw up a question and have 10 responses in 10 minutes." The idea of advice-taking on message boards is "pick what you like and avoid the rest." Even if you don't trust another poster's advice, you usually trust that she's being honest.

On other sites—generally those on which posters have handles—connecting is the point. Women get to know one another, or at least their points of view, and form true bonds, exchanging phone numbers and personal e-mail addresses. I posted a message on iVillage's Betrayed Spouses' Support forum in which I asked about friendships formed. "We are all cybersisters," one user wrote back. "So many of these women have become my good friends," wrote another. "Friends who are there, friends who can identify with the many emotions I go through. Friends who do not judge. Friends who I can lay it all out there to. I would not be here if it were not for this site."

In short, she feels she can trust them.

We are, all of us, the most contradictory of creatures. We need each other, we need to talk, to connect. But when our most intimate and profound bond of trust has been broken, we also need absolute safety to talk about our deepest hopes, fears—and shames. So how do you know if you can trust your invisible audience? Maybe it doesn't matter. Maybe what matters the most is that you dared to speak up and that someone out there was listening.

From the March 2009 issue of O, The Oprah Magazine.