In some ways it's like coping with a grief reaction, and don't let anyone tell you you're being silly. I missed my son so much when he went to uni. It was worst at mealtimes, when I'd wonder what time he was going to be home...and thne suddenly realise that he would be home at all. And bedtime, when I'd hesitate before putting the hall light out in case he wasn't home yet...and then realise again that he wouldn't be home. And I so missed hearing his music coming from his room.
But, like any other grief reaction, I got over it. Especially when he started to send interesting emails which made me laugh.
Don'y feel bad about yourself, or silly - a lot of people feel this way and you will get over it.