S.H.
usually I recommend waiting for boys...but your son will be 5.5 & I think you would just be "delaying the inevitable" as you said.
My concern is that you have now set a pattern where he freaks & you rescue him. This needs to stop. I have always counseled my kids that if they begin something, they have to finish it to the end....whether it be a sports season or a class.
You have 5 months before KG starts. It's time to start emotionally conditioning him to being separated from you. Sometimes in these cases, it's better for the teacher to deal with the child....with Mom totally removed from the picture. Find a class or activity for him.....& step aside. It'll be hard on both of you....but he needs to learn to feel secure without you.
I wish you both Peace.
EDIT: kudos to you for preparing your son academically for school! This seems to be the norm for today's world.....& I applaud you for taking the time to teach your son. As for being ahead of the curve, I think you will be surprised at how many children will be reading (or almost there) as they hit KG - it's a sight to behold! So very, very different from 10 years ago.....