Being on the wayward son end of this type of thing, the best thing you can do, from my perspective, is to give him some space and time. Eventually, i hope so anyways, he will miss his mommy and get back in touch with you.

Try to enjoy your alone time. Do things for you. You put 21 years in preparing him for the day he can fly off and leave the nest. That day has come. You've done your motherly duty in that regard.

Best wishes and good luck!