I read your whole thread (all 3 threads, actually). I skimmed some of the longer posts - I have to work too - but I got the general gist of things. I am writing to offer you some words of encouragement.
I know that every reminder of OM and the A are painful. I feel the exact same pain every time I see a new lacy bra in my closet or see a charge for a fancy pair of boots on my credit card. I also know the fear you experience: fear of saying or doing the wrong thing, of making a mistake. It has governed my life for a long time. (you really should check out my new favorite post, if you haven't already, by ericmsant2: The star is inside of YOU! )
Many of us are in a similar sitch, but we remain fixated on the past and our spouses actions. You, on the other hand, seem to be making a sincere effort to detach and you seem to be succeeding at it. Focus on your modest successes. You have endured a couple of 2x4s from other posters, and came out stronger for it. you did not cower. You learned from their wisdom. I especially liked your conversation regarding your Ws ambivalence about seeing your visiting friend. You handled that way better than I would have. You seem to be becoming a better "you", and that should not change regardless of the outcome. I have learned a lot from reading your posts and their responses.
You are making progress, IMHO. It may seem like you are not, because the process is a slow gradual one. You should really compare your original posts to your current ones. We all make mistakes, and feel bad about them later. We all feel badly about what our spouses are doing. It is how we respond to the setbacks that truly defines us.
Now, if only I could take my own advice and encourage myself!