To raise a child who is comfortable enough to leave you means you’ve done your job

….they are not ours to keep, but to teach how to soar on their own

Although you might actively encourage your children to become independent, the experience of letting go can be painful.
Tips:
Figure out the frequency and method of contact you’ll have with your kids before they leave
Structure your days
Take up a solo pursuit
Connect with others
Take baby steps
Set boundaries