The wayward's fantasy has her literally plucking the husband out, and replacing him with the OM- like he'd always been there (I always picture the old TV show "Bewitched", where Dick York was replaced by Dick Sargent). In this beautiful fantasy, the new husband loves her kids like they were his own, and she his. What about the pesky ex-husband and wife? Well, they become friends of theirs. There's no resentment on anyone's part, and all is right with the world!
Only that rarely (if ever, really) happens. You see, your wife remembers your M as a disaster. You were inattentive, didn't understand her, didn't share interests with her, blah, blah, blah. The new guy? Why he's perfect! He "gets" her! What will happen, given time, is that Mr. perfect will show his true self. He'll become a selfish jerk with your W. I know he will, because he left his own wife the way he did. That's who he is. Your wife's fantasy of who she thinks he is will blow up in her face. When it does- they'll blow up as a couple.
I'd give them three months to two years. Given his former family situation- I'd bet on the shorter end of that timeline.
