I think if the OM was not involved at least I could be clear in my own thoughts that perhaps her judgment and or her feelings towards me where not being clouded by the highs of this new "relastionship".
Realistically someone having an affair like this is usually a "last straw" versus a spur of the moment decision. In most relationships needs don't get met, resentments build up, and just pile up over time. When you're living in the same space there's a lot of motivation to compromise and keep the peace, but usually under the surface there's stuff brewing that isn't getting discussed, usually because both people convince themselves that it's just a temporary issue and will go away on its own.
I read somewhere that for people in a relationship to characterize it as "happy", positive interactions need to outweigh negative ones by a ratio of 7:1. For every one time you come away from an exchange annoyed, you have to come away from seven others feeling good. That's a pretty difficult thing to achieve for most people. If you're shy of that, the resentment snowball is growing.
An affair is escapism for sure, and its usually the result of a chance opportunity, or a thousand micro-escalations that happened without any forethought. What it's really a symptom of, however, is conflict avoidance.
For a relationship to be successful both people need to be willing to blow it up on occasion, argue it out and be prepared to walk if a compromise can't be reached. That takes a lot of strength and self-confidence. For more often people stuff it down and pave over it and eventually you're sitting on a volcano that's ready to blow.
Point is, regardless of the affair one or both of you weren't happy. Usually its just a matter of timing in terms of who pulls the rip cord first.
That's why it's now important to separate the desire for the person, from the desire for resumption of control, stability, and positive validation. Your brain is telling you that getting W back will restore these things, but it won't.
So ask yourself, what do you want and why do you want it?
