I am so glad you guys stay on the board. Tristan, if divorce busting after an affair is the goal, your sitch is about as close to optimal as one could want, yet you are showing all of us how truly difficult reconciliation after an affair is, even in the best case. If I were in your shoes I would be feeling just like you, and would have exactly the same difficulties.
I agree with robx, as long as you're convinced your W sincerely wants your M to work now, humor and lightness are the keys to success. Your W knows what she did, she hasn't forgotten about it. Her seeing it in your face just makes her feel guilty, and doesn't help your M.
Maybe the compromise could be to have some scheduled time for you to express your feelings, and she will hear them without reaction, in exchange for your agreement to not bring them up at other times. Of course you'd have to be prepared for an "ambush", like the restaurant thing, and be strong enough to push it away. No matter what, you will have bad moments, so try not to dwell on them, just keep moving forward.
Don't know if Puppy agrees, but it seems there is a moment when the reconciling WAW really flips the switch back to committment and attraction to their H, and at that point, exposure to OM doesn't "reset the clock" anymore. At that point, I don't think exposure to the OM is dangerous not because of risk of "resetting the clock" but rather just dragging up the emotional garbage again and again, emotional reaction by the betrayed H, etc.