Fibromyalgia since 2007
Kerri, it's called a mistake. There isn't a person alive who hasn't made a mistake. Your husband made a mistake, too, and I really don't think he'll react that way again by the way he held you and told you he loved you.
When I would drop my kids off at school, I never drove away until I saw them go inside. The doors would be locked if there was no one there, right? Also, you would see other parents and children around. Because of this, I highly doubt you would leave him at an empty building.
Please don't beat yourself up over this. I know you stressed out when you saw what you were doing and blamed it on the fog. But, actually, anyone could have made that mistake since the school schedules are different! You now know and you won't make that mistake again. That's what's great about a mistake. We learn from them, don't do it again, and move on. Please feel better.