Quote: I am astounded that she is willing to throw all we have away for some punk kid.
This thought can undermine your resolve to do a lot of the things you want/need to do in your sitch. She is not so much willing to throw away all you have together for some punk kid, as she's willing to throw it all away to gain back her happiness, of which seeing said punk kid seems to be a part of. Also, vilifying him does nothing for you. Sure, he is a low-life piece of crap but I suspect that he's doing SOMETHING W likes or else he'd not be the one in the picture. Maybe it's just that he kisses her a$$, or maybe it's that he's attentive, or more spontaneous, or says passionate things to her, or whatever. There is something to be learned from both her motives to be with him and his personality. Even if he's nothing more than a predator, taking advantage of her, there is SOMETHING in the dynamic that she at least THINKS she needs and wants, and that is possibly something that is missing in her life with you.
I am not suggesting you study the turd for pointers on how to please your W but at the same time I bet there are aspects of him that maybe mirror ways she used to perceive you, especially in the passion department.
Again, study of the OM is usually not anything we want to do but then again, I liken making him the evil villain to writing off our spouses walking away as some kind of temporary insanity. Both ideas can mask a lot of the things we need to look at and change about our dynamic with our wives.