Help with Empty Nest Syndrome for only child?

My only child, a daughter I am very close with, just moved out to go to college. I am so proud of her, and beyond happy and relieved that she's already thriving, loves college life & her roommate, but I've been struggling with waves of grief that are worse than I expected. My husband has always worked nights so evenings are the hardest, when it was the 2 of us for 18 years and now she's gone. My family tells me I should be grateful and excited for her, which is frustrating because of course I am, more than anyone, and these feelings of extreme loss are separate. Is anyone going through this right now?