Like @momofsenior1 I was a stay at home mother of one. It was a very difficult adjustment when my daughter went off to college. My husband would find me just sitting on the floor in the hall crying. She and I are very close (still are and she is 26 now) and she was always a home body (never even went to sleepovers).
My husband still says that when we said goodbye, he wasn’t sure she was going to last the night (she is still living in that city 8 years later.)
I adjusted by visiting her a few times that first semester and finding things to do to stay busy. Those things are harder to do right now. I started cleaning up the house right away (going through closets etc. decluttering). I am still cleaning up (I don’t think that every ends). It was sad, but we all adjusted over time.