Leahsue gave you some really great advice from personal experience.
I can't reiterate how important it is to make sure your son doesn't need to feel like he needs to be on a side at all. It would be awful of your wife to do, but honestly, equally as awful if you stoop to her level.
A's and the reasons for divorce are not kid's problems, they are adult problems. My dad left my mom when I was 17. It was very involved, but in a nutshell, my mother was mentally ill and a recovering drug addict current gambling addict. My dad pretty much raised me because my mom isolated herself from us. My dad waited until he knew I was going off to college. My mother wanted nothing more than to have me to hate my dad because what he had done. Yes, I believe my father left to be with his current wife. My dad knew there was so much more involved I wouldn't understand, he refused to bad mouth my mother or tell me why until I was older. My mother resented me for not hating my father, but he was the person who was always there fo rme and I loved so much, I could not hate him. The point is, I didn't care who was wrong or right. I loved my parents. I didn't want guilt for loving my dad. I didn't want to be involved in their relationship, I just wanted their love.
My ex me for OW when my D10 was 6months old. When my D was about 4, she mentioned OW's name (who was wife at that time). I made a face. She asked me why. I said I just don't like her. Well, huge mistake, she spent the time at her dad's house saying to OW "I don't like you because my mommy doesn't like you!" It was a wake up call. My D should not have to live like that. Those are our problems, not hers. I am kind and cordial to both her father and OWW now and have been for a while. because I hate to see my D's discomfort.
You would be really surprised at how perceptive these kids are. My D10 is observing dynamics between my ex and his wife that were the damaging dynamics in my M. She said to me "whenever OWW tries to teach me something, she looks at daddy not me, because she is scared she is saying the wrong thing" This is the perception of a 10 year old!!!
My point being is take the high road. Your W may chose not to, but if you do, it will pay off in the long run. Kids KNOW the truth.
Put yourself in S13 shoes. He wants to be a teenager, no someone having to choose which side to be on. And as long as you can assure your boy that he doesn't have to chose one, your relationship will be strong.
