Stormchaser, just reading your post here and it brings me back to last year for me. My W told me near the beginning of last year that she nearly had an affair but chose me. Now we never did any work together or individually to find the reasons why. We tried to do it alone but I did none of the DBing and we got into arguments when she started building contact with the work colleague again. It started again within 4 months of original admission of attraction. I also think he pursued her and she would not cut it out. The triggers were intense for me and caused more problems between W and me, now she has left saying she is done.
Now I didn't see the remorse that people say, I didn't see an effort on her part to work on herself. I was supposed to trust her completely from the beginning and just let it go. Her contact with him at work was 'not important', and I was being petty.
The reason I write, is when you talk about the setbacks. My W wouldn't grasp the concept of what she had done and the setbacks tore us apart. I know how hard it is and I'm sure you have done a much better job than I did last year. I wish I could give you advice and I wish I had learnt what I have now last year. I can only say to stay strong, try to recover and I hope you can communicate how difficult this is in a way she can understand. I wasn't able to get that across to my W, even when I had her read some things on recovering from an EA.