These are classic symptoms of hypervigilance:
It is fairly normal following a trauma, such as infidelity.
After doing the same things as you, I finally came to the realization that I have no control over someone else's actions and therefore there was nothing I could do to prevent another affair. If my wife cheats again, I'll just to have to deal with it when it happens. Snooping and playing all the what-if scenarios in my mind, just caused me unnecessary stress and anxiety.
What helped me the most was daily meditation and vigorous exercise. I found that by calming my mind, it would help the obsessive thoughts from being blown out of proportion.
You'll find that R teaches us a great deal about ourselves. So sorry for what you are going through.