I only have one child and when she went to college in the fall of 2007 (2 hours away), I was very sad. I was very involved in with her school/sports and then it was all gone :(
I got Blackberry so I could text (my old phon did not have texting) so we kept in touch that way and phone calls. She brought her car to campus after the first semester so we would meet in the middle at least once a month for dinner and to replenish her snack supply.
I started to enjoy the "me" time after the first couple of months, but it was a major adjustment. I started spending more time on my hobbies so that was good.
In 2008, I moved 500 miles away (due to job being moved) so it is harder now. She is a Senior now and graduates in Dec. and has no desire to join us - VA is her home and that is where she wants to stay. I miss her, but we talk daily and I fly her up here every 6 weeks or so.
My advice is enjoy this new time that you have and "find" yourself again. I love being a mom, but I also love not having the daily responsibility any more. I used to have to make dinner every night and now I can skip if I want to. Little things that I have come to enjoy - less laundry, quie house.
Maybe you can set up a monthly lunch/dinner with him and that will be your special time. Good luck! Meghan