Growing up is hard to do

My oldest son is leaving for college on Sunday. I thought this would get easier but instead I find it harder each time. It is like a piece of my heart and soul leave. I admit that there have been times when I wished he could go back early because he was being a smidgen difficult but in reality I really didn't want him to go at all.
Today I was hanging pictures in my room at school and talking with one of my friends. I had to stop hanging the pictures because I started to cry. She took over and did a beautiful job of hanging the pictures in a place where I could look at them all the time. I felt a little silly for crying but I realized that I am having to once again let go.
I know that we raise our kids with the final outcome being that of letting them grow up, be adults, live their own lives, develop their own family, etc. What no one bothers to tell moms is that in order to do that your heart will be ripped out and you will feel an emptiness. Hence the term "empty nest". Now my husband is looking forward to the day when all the kids are gone and a little piece of me is there as well but to get there....well, it is a hard road. I told my son today that I was sad to see him go because I liked having all my boys home. I like taking care of them and having them here. Yes, they fuss and argue and drive me insane (a very short journey) but all in all these boys and their daddy are my life.
I look at my other two boys and realize that in two years I will lose another one and a short two years after that I will lose the last one. I refuse to think about that right now.
I guess I don't really lose any of them but it sure does feel like it.