Wow Gyps you need an outlet for that prose girlfriend! I agree with you wholeheartedly. Especially your conclusion:
"It's how we get up from this shocking experience that defines who were are.. in the now, the present, not the past."

The only part of your post that I do not agree with 100% is:
"Are the spouses who leave 'bad' people? No, but their actions are irresponsible." I guess we can debate the bad versus irresponsible or bad versus weak etc. Bottom line, I accept that I may not be perfect (although I have NGF fooled for the time being / and I still get e-mails corroborating that from of all people the XW) but nobody will convince me that cheating on your spouse, repeatedly lying to their face and breaking up a family (usually with small children involved) is the act of a good person. Good people are not selfish, good people are respectful. Good people act like what you described in your opening paragraph.

CTH, I have never bad mouthed XW to anyone who knows or knew her. Especially not our daughter...like you, I boost her but not at my expense. I am not familiar with your sitch but I have a hunch that it is no different than most. Have you forgiven and accepted her choices? I have no clue....however, without any other information, I would rather have you as a friend (even if you don't listen) than a woman who looks (probably has been looking since before the bomb) for greener pastures and who I suspect has probably found it (in her mind anyway).