Congratulations! I remember dropping my first off at school and his roommate's mum was there at the same time. She said to me, "Come on, admit it! Isn't it great to have them on their own? Haven't you been waiting for this" And I had to admit that, no, no I had NOT been waiting for this, and that I LIKED having him home! I suppose this is irrelevant, but his roommate's mum had more or less disowned him by semester's end, while my son was still more than welcome at home.
Regardless, I have three children, and they have all left for college now. They visit home often, and feel comfortable here, but enjoy it at school, too. I think it's the best of both worlds. I was SO nervous when this change first started, as Dh and I had been parents for 20+ years. What would we do without kids in the house all the time?
Well. for us, it has worked out well. We had almost lost touch after so many years focusing on the kids, but when they left, we seemed to have a Renaissance. We now take short, 3-4 day vacations together often, and we are more connected than we've been in years. The kids are all doing well, and we are doing well without them - truly the best of both worlds!
This is a really difficult adjustment! I give you credit for having a son who is happy to take on the chanllenges of independent life, and for still being there for him when he needs you. He won't forget the way you allowed him his freedom and were still there as his rock. I wish the best to you, your partner, and to him. I am sure he will thrive!