Mike .. I completely relate. My W OM is a personal trainer .. she introduced him to our S a month after she moved out as "A friend" and had his kids and mine together as "play dates" ... that deep down betrayal not only of the relationship .. but also of the family unit has no stronger pull on our emotions. Later she finally confirmed my suspicions ... not that it made things better other than to confirm I was not crazy.
You have to go LTR .... and most of all the hardest part is the detachment phase, my advice .. what worked for me .. find a GAL activity that you actually can sink your teeth into. Something that you look forward to because of the release you get from all the emotional stress this sitch has found you in ... just remember .. you did not ask for this, go do you for a bit. The A between your WAW and the OM has to run its course. She needs to end it ... and not be able to use you as the excuse that would further justify her actions.