I'm going to echo some of what has already been said. An affair, whether EA of PA, is a symptom of dysfunction. Obsessing over what has or hasn't happened is not healthy, and I suspect you know that.
Instead of worrying about gathering evidence worry about addressing the issues in your relationship. But here's the key - don't do it only to win back your wife. Do it because, as you said, she woke you up to some of your issues. Now it's time to work on them. If not for this relationship for your next.
Me-38 W-38; T-15 M-12; S10 and S6 BD - July 2016; EA confirmed; confronted Aug 2015 EA dissolved 12/2016
Never make someone a priority when all you are to them is an option - Maya Angelou