Thanks for the background, that helps paint a more clear picture.
You've identified that you have some issues to work on, and that's good. The next step is to realize the reality that this is ALL you need to work on.
The rest of this stuff is not your business. Your wife has told you explicitly that she wants you to stay out of it. If you have even a scrap of respect for her this should be a very important factor in what you do next. They are dealing with a new relationship which has quickly hit the rocks and I'm sure they can handle it just fine. If they *can't* handle it just fine then maybe they'll break up... also not your business.
I know we've already said this, more or less, but I hope you really take it to heart and learn to respect your wife and the people around you as adults who are quite capable of taking care of the details of their lives. If they want help, they'll ask.
I wish you luck, I really do. However, it seems a foregone conclusion that until you can learn to live your own life and let others live theirs... you are in for some more drama and heartache.
Me: male, 40, straight, single