Brian, You can't change what has happened, but in the future, come here to talk about things and do not discuss your situation w/other people as you have discovered, things do get revealed and very quickly. If the co-worker liked your family just so much, she would have kept what you said to herself and not revealed what was told to her by you. The old saying "a dog that brings a bone will carry one" is so true.
Affairs have to die a natural death. If they are exposed, that doesn't necessarily mean that the affair will end. In fact, it may push them together more so because they want to protect each other from the cold, cruel world. As you have now seen, by exposing the affair, your wife is now wanting a divorce within a month. She will use every justification in the book to justify why the affair took place and why she felt the need to so. Of course, it's not you. You didn't put a gun to her head and tell her to this. This affair is all about her.
It's going to be interesting to see how this information plays out in the work place. One may be reassigned to another office and/or building, but they aren't going to be very comfortable being together w/others watching the drama unfold and others whispering and pointing fingers at them. Then again, the om may break it off w/your wife or vice versa.
Brian, the only way your wife sees saving face right now is to talk of a divorce. If she wants one, then allow her to do the heavy lifting for it.
As for the affair partner, well...I would let him sink in his own mess for a while. I wouldn't say one word to his wife because you don't want to get drawn into their drama. For all you know, she may already be on to them and/or has been told of the affair as well. If she should approach you about the situation, then you can share what you know, but I wouldn't be the initiator in advising her of the her husband's affair at this time. Allow the affair drama to play out and die a natural death. It may end sooner than you think now that it's been made public. I would suggest that you start thinking about a consultation w/a lawyer, if you haven't already done so, and get educated on what you are entitled to, just to be on the safe side. Whatever you find out, do not share it w/your wife. This info is for you only right now.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.