Validation is very important. Do not push your Point of view(POV). Show you understand HIS POV. Compassion and Empathy. Listening is a very important skill to have right now.
Actions speak louder than words. Watch his actions and control yours......
Be very cognoscente of his reactions to your actions.....
Do not take his negative POV as your own. "Smile and wave boys" Project that you are happy no matter how HE feels. You can empathize ...."You look XYZ."
Listen, listen, listen.....Less talking the better.....
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712