Just a couple final thoughts on this and then I've probably said enough. More than enough, probably.
First, for anyone who has been an involved parent, there will be empty spaces when a child goes away. We've already said that trying to maintain our relationship with our children when that happens as if nothing has really changed is... well, destructive. A change has occurred. We need to acknowledge that, be responsible for our own emotional well being, and allow our children to thrive independent of us.
Frankly, one of the best ways to do this is to get involved in serving others. If you are a person of faith, for instance, go to your local place of worship and ask what you can do to help. I know my church is ALWAYS in need of people who will help us accomplish our mission and better serve the needs of our community.
Second, make sure there is some structure to your life that will keep you connecting with your spouse. When it comes right down to it, a lot of married couples relate to each other primarily through their kids. I think it is pretty obvious that doesn't make for a very healthy relationship, and that it will mean big trouble when the kids are gone.
As an example of what I'm talking about here, Linda and I still have "family dinner" together. Though it is just the two of us, we still prepare a family meal (even if it is just a bowl of oatmeal for me and peanut butter and jelly for her), sit down at the table, pray, eat slow food, and talk about our day. I'm glad we do.
Well... maybe one last thought. Realize that because this is a major life passage. it is a time when people do lose their way. Alcohol can be a problem (and this happens more frequently than you might think). Anger (a secondary emotion which can be triggered by a perceived loss of control) can mask what is really going on inside. People have affairs, sometimes physical, sometimes virtual, sometimes with the internet itself (could a person have an affair with Facebook?). I could go on, but I think you get the point.
Guard your heart and soul. Stay connected in your marriage, in a life-giving community, and with friends. Give back. And in so doing, enjoy a stage in life that while difficult, is a great opportunity as well.