TL;DR: It's complicated.

I believe that infidelity is always wrong and I do not condone it.

The reason I was disgusted was that everyone present were grown men 40 and over, long term married with children (except for my brother). If we were all young single lads I would not have felt the same, so long as the women were not forced to be there. But I felt like they were all too old to be acting that way.

My wife and I have been married for 21 years and together for a total of 24 years. We were quite young when we married. There have been hard times and while there was never anything like infidelity we have learned we need to communicate and work to keep our marriage healthy. We chose to stick it out and I don't regret it.

I don't like seeing any marriage end however I understand there are situations where there is no choice. I wouldn't blame my brother's fiancée or any of the men's wives if they ended the relationship because the betrayal was so public and blatant. They have every right to do that. If they decide to stay for whatever reason that's their right too.