Ive read through most of this thread, I didnt go back into your previous threads.
Fist off, Sorry your in this boat, This is a tough one. I went through something similar with my first wife but she was going through mental issues so it was alot easier for me to dismiss as her condition and the fact that her condition was forever and she was cheating made it easier for me to move on.
Somewhere in here you posted that she seems so happy on the outside and questioned if she really was happy. You need to get there. You need to get yourself to a spot to where you come across as genuinly happy. When my Ex and I were going through this, I wouldnt call her at all. My responses to her were short, to the point and generally upbeat. Once she saw me being happy and moving on, not that I was dating anyone else or anything like that, I just didnt let HER consume me, she started pursuing me. First signs of me turning to jelly, she would be turned off. So reverse the roles. Make it so that she would be going OMG is he really starting to be happy with out me?? Thats when questions will fire in her head, just like it made you.
Stay strong. Keep moving forward in life for yourself and your son. Make sure you are a good role model for him and that would include handling this situation the best you possibly can. Regardless if things work out for you and your wife, your son will remember what you did and how well you handled it. Show him how you deal with a tough situation like this. That was one of my biggest motivating factors for me. It helped me stay strong and stay the course.