Then 3 hours later, I received information that confirmed she was actively having an affair. I had managed to stop doing all the things on the list except the spying. And now I can't undo that. I am paralyzed and devastated. I don't know what to do.
Her infidelity doesn't change what your response should be. In fact, it makes it even more important for you to follow the DB principles if you're still interested in saving your M.
You should still be doing what you started out doing. It's going to be more difficult, though, because of what you suspect or know about the infidelity. No need for further discussion with her about it right now. I think you should stop the spying but that's my opinion. However, if you can document the situation in case you need it later in order to prove infidelity, that might not be a bad idea.
