I'm glad that you've decided to stick by your marriage. You are dedicated to your wife, and family. She has turned into another person. Give her room to "snap" out-of-it. Internalize it as an act of love. Remember the vows, "for better or for worse?" Right now, I would not pursue her. Instead, keep doing what you are doing. Michele calls it a 180. You need to understand, that your wife has changed. If you pursue her, you'll push her further away. In her presence, be upbeat, do not ask questions, argue, beg, or cry. Also, if you snoop, it will not do you justice. In fact, you might not be prepared for what you'll find. But that does not necessarily mean THE END. As you know, people do change. As for now, please take care of yourself, LOVE on your children, and participate in relaxing activities.
You said: "Cheating is the lowest form and most painful thing in the world." Yes, it hurts. I would never wish this upon anyone. We do not understand why things happen. However, do not give up. Please take time to read the book, and keep on visiting!
I think you're amazing for making it this far. Keep it going!