L.A.
This is going to be a little strong.
You and your attitude are the most important influence on your child. Will be for a very long time.
The fact that YOU do not feel ......You are setting the tone for your son. He is in tuned to your reluctance, to you projecting... IF you want to change HIS perceptions and security, and love of school, YOU are the one that needs to be on board.
If you feel like HE is not ready for school, because of his maturity, emotional needs...then you could homeschool him. But stop and think, why is it everyone else's children are happy and able to make kindergarten work? Attitude. Heck if I could have kept our daughter home forever, I would have loved too, but she was ready. I could never have held her back.
You do not believe in all day school, your son was in an accident, you changed schools, he has anxieties... What he needs is stability and he needs to know his mom believes in the choices that are being made 100% of the time. Get on this horse, or get off, but whatever you do, leave you attitude for your husband in private, and act strong for your child.
I am sending you strength.