My husband is sleeping with my colleague

An older colleague told me of a neighbour who had issues with her husband. This woman - let's call her Kay was convinced that her husband was having an affair but couldn't prove it. She laid a trap for him, put out all the FBI moves and eventually found out the truth. The hubby was really having an affair but that was not the shocker, the real shocker was that the side piece was her colleague, actually one of her subordinates in the office. We'll call the side piece Betty.

Kay had risen to director level by the time she was 29. She had the power to deal with Betty because she was way below her on the corporate ladder even though the age difference wasn't much.

Kay biggest dilemma was the fact that she trusted Betty as of all the people in her team, Betty  had become some sort of backbone. She had helped to keep Kay grounded as she navigated the challenges of being a young executive reminding her of the things that really mattered. Kay in return mentored Betty.

Kay's biggest dilemma now was Betty's name had come up for promotion. Kay knew that Betty's direct bosses had put her name forward because they wanted to be in her good books. Kay did not believe Betty deserved the promotion as she had been at her current position less than a year and was struggling at it. She believed that training and international secondment was what Betty's career needed. Promoting people to levels of incompetence had never been Kay's style.

The biggest challenge was that Kay found out about her husband's affair in a rather public way and if she denied Betty a promotion, tongues were sure to wag. She was in  a serious dilemma and wondered what to do. This coupled with the fact that she was dealing with the hurt of her husband's betrayal. She had the mind to take a vacation and skip the management meeting so that Betty's track record could speak for itself; but Kay knew she couldn't. There were young people on her team deserving of upward movement, top talents she wanted to push in order to gain management recognition. She was at a loss and didn't know what to do.

Now whether my colleague was saying the truth or making up the story to pass time while we waited for a long overdue meeting, this story brings to mind how uncomfortable finding out your significant other is cheating with a colleague can be.

What would you do if you were in Kay's shoes? are the dynamics different if the colleague is senior, junior or on the same level? Is cheating more painful when it's with a collegue?

I'd really like to hear your thoughts.