I am so sorry Jim. You have really been doing weathering the toughest part (piecing) like a champ.
Mind if I ask how you don't have hard evidence but you know it's happening again? Is it a gut feeling? Putting pieces together? Heard from someone else?
I know this doesn't help, but this is truly your W's loss. She had the chance for her husband to trust her in a situation where most guys would have booted her out the door.
Know that you have done everything you could in a gracious loving way.