In reply to Morty:
Our two lads went off together, which wasn't so bad - we could have done without the effing catastrophic car crash on the way there, which complicated the logistics of getting one to Bristol and one to Exeter no end.
When the youngest went two years later, my wife was distraught. She couldn't cope with open bedroom doors upstairs at all.
It took about three months to get used to it, and then three months later the first one came back (the other buggered off to the US, and came back a year later, bringing a useless tart with him. Fortunately, she's gone back to Florida and with a bit of luck someone will feed her to the alligators, but she's so bitter they'd spit her out. But I digress.)
You'll get used to it, you'll enjoy the extra space, and then probably have to get used to them coming back again, maybe more considerate, maybe not. All you can do is remember that you did all that you could to prepare them for this day. I'm sure you did a fine job.
We've got two out of the three in residence again, for the foreseeable future