It is now your time. Time to spoil yourself. Go have a manicure. Have a facial treatment. Buy some glamerous lingerie. I have done all of these and am revelling in my independence.
The answer is to GET BUSY! (It will take your mind off it if nothing else.) Find something you love doing, whether it's a course or even fundraising for a charity. It might help you remember who you were before you were a mother. Good luck!
Even if you have to give up your career to bring up children (a very worthy career in itself) try and keep up an interest or hobby so that when the children do all leave home, you're not at a loss for something new to take up and get busy with
Get yourself a little job, make up some cute care packages for your children - little things you would know they like and send them, take care of someone in your area that needs it - a sigle parent, an old person, start a walking group, just get over it and get moving!!! Be proud that you have helped your child move on in the world and now you have the opportunity to have more time with your husband!!! Oh la la!!! :)