When my middle daughter went to U of Washington (we lived in Colorado at the time), I cried every time I walked by her room. It will take you some time, but go ahead and cry - it's natural to miss your baby after all you've been through together. Just be joyous for his big step in life.
Thank goodness for email!!
You and your mom should go grab a coffee somewhere and build back your relationship. That first step is hard, but they all are. You'll be glad you did.