
Here are a few excellent resources for you to utilize now and after your separation/divorce is finalized:
"The Divorce Workbook: An Interactive Guide for Kids and Families," by Ives, Fassler and Lash
"My Parents Still Love Me Even Though They're Getting Divorced," by Lois V. Nightingale
"Dinosaurs Divorce: A Guide For Changing Families," by Brown and Brown
"It's Not Your Fault, Koko Bear," by Vicki Lansky (a read-together book)
As difficult as this situation will be for your son and the both of you, it appears that he has two loving parents who will make sure that he continues to feel their love.