Debbie,
I understand so very well the feelings and thoughts you are having as your adult child leaves for college!
After my son announced he was moving out at age 19 (he's 30 now), the night before he moved out, I said to him, "Dinner's ready" and I started to sob, as I new this was his last 'official' nite at home..
When I drove my daughter to her college dorm when she was 18 (she is now 27) i cried all the way home and told myself, "I know longer have reason to even come home"

Days later, I would have to pull over when her favorite songs would come on the radio and I would cry, again..
I understand the emotion and void that you are feeling..it is a huge and emotional milestone for parents, when the 'kids' leave home.

My son and daughter have traveled a lot and often to dangerous places, and I had to get used to trusting them and trusting fate. This was very hard to do..
I am proud of them..They have strong wings as they navigate their own lives..
As time has passed, I have peace of mind...it took a long time for me, as my children were the most precious blessing in my life.

I am so fond of this piece by Khalil Gibran from his book, "The Prophet"
These are a few lines from the chapter titled, "On Children."..

Your children are not your children,
They are the sons and daughters of Life's longing for itself,
They come through you but not from you,
And though they are with you, they belong not to you.

You may give them your love, but not your thoughts.
For they have their own thoughts.
You may house their bodies, but not their souls,
For their souls dwell in the house of tomorrow.......
_______________________
Gibran goes on to compare the child as the 'arrow' and the parent as the 'bow' who propels the arrow forward...to their own independent lives....

The love, though, will always be there...
I didn't want to go off topic from the original intent of the thread, but
I hope my sharing has helped you to know that I understand your feelings, and that it gets better as time goes on..
Many, many hugs from Hope4thebest xoxoxox