My Baby Is Leaving Me...

Tomorrow is DS's first day of preschool. I suppose I should be happy that I'm going to have a few hours to myself, but I'm really not. He and I are very rarely apart from each other. Even now, when he has therapy, I usually have to stay in the room with him. When I'm not standing right next to him, he will look around for me... just to make sure I am still there with him. I am just beside myself with worry... my stomach has been upset all day.
I know he will be fine, but will I?