I have detailed this in another of my threads, but soon after d-day, I guess about six weeks or so, I had a ONS. My WW had moved out on d-day, and was more or less living with the OM, leaving me completely alone in a city where I knew nobody. I spent days in front of the computer...both here and other support sites. I met a number of friends in the same boat, as well as some "friends" who were involved in the wrong things. One night, after partying, it happened. And it was empty. It was almost unpleasant, I guess because it was strictly for revenge...I almost felt angry during the act.
The scary part is, my WW was coming over the next day to watch the dogs, and found some evidence of the act. So she now knows that it occurred. I felt better once she knew - I guess my sense of guilt is overdeveloped.
It did not make me feel better about "getting even" - It made me think less of myself in general. I do not view myself as a WS, though. The bonds of our marriage were broken when she chose to move out, and persue her relationship with the OM. She also filed on me soon after d-day. This still doesn't make it OK, but I feel that it doesn't rise to the level of me becoming a WS.
My advice to any BS is to keep your conscience clean, though....tkae the high road for this time period (or always, for that matter) and see this as a growth period for you personally. If you need to, see this as penance for allowing your M for getting in the state it had before the A occurred. That is how I am viewing my time right now.
TM