Sending first kid off to college

Boy, can I relate to how you felt.
My daughter (the oldest of our blended family kids) was the first to leave for college. I cried like a baby in the shower the morning we took her to the airport to catch her flight to Kansas (KU) where she had a full-ride softball scholarship waiting for her.
Her mom and I split up when my daughter was only seven and I was a full-time single dad for eight years before I remarried. We were really close since I was both parents for several years and was always involved in helping coach her various softball teams up until she headed to Kansas.
Enjoy the fact that your son is so close to home even though he's living in the dorm at school.
It was a long way from SoCal to Kansas and I only got to see my daughter when she came home for either the holidays or KU came to SoCal for softball.