I just graduated from high school, but I am also feeling the same way. I think it's important to remember that graduating is simply another stepping stone. It doesn't mean that you can't have fun anymore or that you can't see your friends. Sure, people will go their separate ways, but I'm sure there will be plenty of opportunities to get together again. Just as you have made great friends in college, you will also make great new friends in the working world. Best of luck to you