... and currently 67% of second marriages end in D... and 74% of all third marriages end in D
Overall the odds of staying M to an A partner or otherwise aren't overally all that good.
I would think once I got to the point of letting a S go because of D I would try to think less about the S and how they carry on and really more about myself.
I could care less about my Ex and his W or their kids unless its something that directly relates specifically to our shared child. I've got better things to do and more important things to take care of!!!!!