My husband(34M)'s friend(34M)'s wife(30F) doesn't know he has been cheating for almost a year. Should we get involved?

Throwaway account because I really don't want anyone involved to recognize me or this story.

My husband (34M) has known "John" (34M) for about 15 years. They are not best friends and they are not extremely close anymore because they have very different personalities. However, the four of us (my husband, me, John and his wife "Emma" (30F)) see each other around once a month. We usually play board games, have dinner and catch up. It is very rare for my husband and John to spend time together without the rest of us.

I've known John and Emma for about four years. Emma and I are not close friends, but we have become friendlier over time. She is genuinely a kind person and I enjoy spending time with her.

John and Emma have been together for about five years and got married one year ago.

Last year, the four of us went camping in the mountains together. We had a great time, so we decided to repeat the experience this year. We spent several days together, and because you spend so much time together while camping, I felt like Emma and I actually became closer.

Two days before this year's trip, my husband accidentally found out that John was talking to another woman. He confronted him, and John admitted that he had been cheating on Emma.

My husband chose not to tell me before or during the trip because he didn't want to ruin the experience for me. He told me everything after we came back, and honestly, I am grateful he waited.

This is not a rumor. John admitted it himself.

At first, John told my husband that he thought he was in love with the other woman, that he didn't love Emma anymore, that he couldn't stand her complaining, and that he was considering divorce. He described the other woman as someone who made him feel excited and said their relationship was very sexually fulfilling.

A couple of days later, John changed his story.

He told my husband that what he actually wants is to have both. He wants Emma as his wife and also wants to be able to have sex with other women. He basically said he likes the idea of having a wife and a mistress.

My husband did not support or encourage him. He tried to stay neutral because he doesn't feel like he is the person who can decide what someone else should do in their marriage.

The advice he gave John was that he should have an honest conversation with Emma about what is not working in their marriage instead of avoiding those conversations, maybe this way he would stop cheating.

However, based on everything John has said, we both feel that telling him again that he should be honest probably would not change anything. We don't believe he would confess because he feels guilty or because he wants to do the right thing. We think he would most likely just become better at hiding it.

There are also things that make me wonder if Emma already feels that something is wrong.

This is only my interpretation, and I could be completely wrong, but I feel like she might sense that something has changed.

Before we knew about the affair, John and Emma went on a trip with a larger group of people. At one point, John said he wasn't feeling well and wanted to go for a walk. This was unusual for him. He disappeared for several hours and stopped answering his phone.

Emma became extremely worried and thought something serious had happened to him. She had a panic attack because she couldn't reach him.

When John came back, he told her he had felt sick because of alcohol and had fallen asleep somewhere.

Later, my husband found out that he had actually gone to meet the other woman.

From what I understand, this has been going on for months. John has been making plans with the other woman, including renting cabins and spending weekends or weekdays with her, while telling Emma he has other plans.

The part that has been bothering me the most is that, just before our camping trip, Emma and I met one-on-one for the first time.

Somehow, the conversation turned to cheating.

She told me that she is afraid that she would probably forgive her husband if he cheated.

But then she also said something that has stayed in my mind. She said she genuinely doesn't understand how people cheat because if she ever cheated on someone, she wouldn't even be able to look them in the eye afterward. She couldn't imagine pretending everything was normal. It goes completely against her values.

Now I cannot stop thinking about that conversation.

I keep remembering the camping trip, her laughing, cooking, spending time with us, while not knowing that her husband had been living a double life for almost a year.

I don't know what my responsibility is here.

Emma is not my best friend, but she is not a stranger either.

The hardest part for me is that I don't feel like I am the right person to tell her.

I know many people will probably say "tell her immediately", and I understand why. If I were in her position, I would probably want to know the truth too.

But I don't have a close enough relationship with Emma where it feels natural for me to suddenly come to her with something that will completely change her life.

At the same time, I cannot continue having the same relationship with them.

I don't think I can sit with Emma, have normal conversations and pretend everything is fine while knowing something this important about her life.

My husband also does not want to continue this friendship as if nothing happened. He does not support what John is doing, and we both feel uncomfortable continuing to spend time with them. We are thinking about slowly distancing ourselves and no longer being part of their lives.

I'm struggling with how to navigate this situation going forward. I don't know how to interact with Emma while keeping this secret, and I don't know whether the healthiest thing is to distance ourselves or handle this differently. Has anyone been in a similar situation? How did you deal with it?

I am genuinely looking for advice because I feel awful for Emma, but I also don't want to make a decision that causes even more harm.

TL;DR: My husband's acquaintance John has been cheating on his wife Emma for almost a year and admitted that he wants to keep both his wife and a mistress. My husband found out after catching him, and I found out after spending several days with John and Emma. Emma doesn't know. I feel unable to continue acting like everything is normal while knowing the truth, but I also don't feel like I have the relationship with her where I should be the person to tell her. We don't know if we should get involved, encourage John to confess, tell Emma ourselves, or simply distance ourselves.

Edit: This post was written with AI because English is not my first language. The story is true, and I am genuinely looking for advice and outside perspectives because I don't know what the right thing to do is.