Here's the deal Future. You won't be able to trust your wife until she starts being trustworthy. Once she's been trustworthy for a period of time the trust will return.
If your wife wants to win your trust back, no-contact will be easy to verify because your wife will invite you to hold her accountable. If she baulks or makes excuses about participating in accountability measures, you know she's leaving wiggle room for contact with OM and it really isn't worth going down the piecing path with ongoing contact.
I know GH31. I wish I could just trust her, but I can't, and won't be able to for quite a while. I will struggle with that, because I'm a naturally very trusting person, and I want to think the best of people. I am encouraged by how we've been with each other for the last several months. Whereas last year when my W was having her secret A my gut told me something was wrong, now I feel she is being honest with me. Of course that might just be because she has no reason to lie right now. If we decide to reconcile, have a tough few days or weeks, and then she gets some secret message from OM, I know I can't trust that she won't turn back to him.