It's sad to hear that this is having an impact on your S.
The fact that he has a negative opinion of the OM, and the fact you are seeing visible negative changes in the W speaks volumes. You are a good man and doing things right. Her negatives define her and is no reflection on you.
Me: 43 W: 37 Together: 18 M: 15 D: 8 yrs old ILYBNILWY: March 2011 She Filed for D: August 2011 She moved out: Sept 1, 2011 Reconciled: May 2012 Divorce Case dropped: July 2012