No you can't control but you can decide not to FOCUS on it so much. You want to blame someone...I get that...but looking to place blame will keep you in a hole.
Quit looking where to put the blame and pick up and move on...start living your life, show your son that you can be okay, that he can be okay...quit feeling happy when H is sad, or angry that he is "doing this" to your son, or hating when H sounds happy, hating MIL...all of this wild emotion flying around is probably having more of a profound effect on your son at this point then where his father is...
Your H's M will be in the picture until she passes on...looking and blaming will not help you and will definitely not help your marriage...what will help everyone is for you to take care of yourself and your son and forget what everyone else is doing...
