My son goes to uni in a month and I feel like I'm grieving.

I was feeling alright about my son going off to university, but I've been a complete mess ever since I had a horrible dream a few nights ago about him moving into halls. I'm extremely mindful of his happiness and excitement about it, but the idea of him being gone makes me nauseous, and I can't stop crying. I have no idea how I'm going to survive the upcoming days, weeks, or months. I'm sure many parents on here have dropped off their children. How are you managing?