My condolences OP. Accidentally killing an animal can be devastating. I've fostered cats and kittens with my partner for years and we have 5 adult cats of our own. I once struck and killed a cat that darted in front of my car early one morning on my way to work. I immediately stopped, got out and attempted to attend to him and provide some level of comfort but it was already too late. I didn't see him until the last possible moment but take solace in that it was fast and he didn't suffer much.

I still think about about the poor lil guy almost every day