You are making the right decision. Your child will gain so much from the early school experience. Including beginnings of peer interactions, self reliance, since of achievement, and so much more. My child started PPCD at 3. He has been in the school system a hard to believe 10 years now. He has grown so much. Starting his school life early, and getting him used to the routines of school has been a wonderful foundation for him to build on.
Having to let your child go, and put them on a school bus at 3, will be one of the hardest things you have to do as a parent. I have the memory ingrained in my head. At the moment I had to let go, I was looking at the pack back my child carried. The backpack was bigger than my child. I thought he is so small, and to young. The pain in my heart was unbearable, but I had to let go. It is the same process of letting go, a parent goes through when sending their child off to kindergarten for the first time. Only we have to go through it when our child is much younger.
There are things the school can help your child with, that we are not always able to because we are parents with deep emotional ties to our children. Sometimes our kids need someone with the objectivity to resist the parental urge to jump in a rescue. The Teacher is sometimes better able to step back and let the child try their own feet first before rescue.
Even if your child is going to school, you can still stay involved. You are just adding to your team, additonal caring people, with the same goal of helping your child to achieve their fullest. I am sure knowing that doesn't help lessen the heart pain any now; but a few years from now when you look back, you will be able to smile, and know it was worth the pain you had to go through to let go.
Stay strong. You are a great loving Mom, and you can get through this new transition in your child's life.