wow ... i got a lot of "vibes" from reading your post that might be of some help to you figuring this out.
one thing is that now that finally fessed up and told you the things you already had a hunch about, by her owning up to what she shes been sneaking around behind your back and hiding from you all along gives you the "relief" of finally getting that justification you deserve.
also by her saying shes gonna wait b4 introducing your son to her new " mr wonderful" it kinda seems like maybe now her wonderful new life without you that she had her hopes set on happening might not be as peachy keen as she planned on so shes been having some 2nd thoughts about what she did & maybe her life with you wasnt as bad as she thought it had been.. & now shes thinking about what she gave up only to wind herself up in whats starting to look like might turn out being an even less than ideal spot... all of which gives even me a touche kind of feeling so perhaps deep down you see it as the start of her getting some of the payback shes got coming her way and gives you a wee bit of some satisfaction out of it.
also now you two are divorced, your not wearing those rose colored glasses anymore so now you are able to start seeing her in a whole new light and shes beginning to look a lot less of the woman you had once believed deserved to be put up on a pedistal to you now and gives you a little "good riddence" glad shes gone feeling.
so yes, karma, closure, justified, satisfaction, vindicated, ...