Arthur, Thanks. I would like to help you if I could. I have read up on your situation. Your advice would be somewhat different than Ping's advice, but in some respects they would be the same...
I'm not sure you would be able to hear, handle or take my advice on your situation because I think you would be scared it may backfire. Your wife IS having an affair. That is clear. You NEED to snoop until you get the facts. A person can't make wise decisons without all the facts. Once you get the facts, then the snooping should stop. Until then, get all the facts you can so that YOU can make an intelligent decision based on those facts..
From what I see with your situation, I would encourage a different approach from Ping. My belief is that I don't think a man is wise to let his wife have her cake while he thinks he is fighing to get her back. That is the position I will take if you want me to help you.
Let me know what happens. First thing is you need to do the "snooping" to find out what really is going on. I am sure she is interested in another guy. YOU need to be sure. DO NOT ask her. She will lie and blame you.
In the meantime...
Stance, grip and alignment.
Work on being happy. Pursue your own interests and hobbies.
Start there and let me know what you find out. I think you already know. You have to be able to be honest with yourself. I know it is a shock to think the woman you love has another man, but the sooner you admit it is true, the faster and better you can deal with what you have to do to save the relationship...