I've never hit an animal but I was in the passenger seat when my mom hit a dog a few years back. It was very traumatic for both of us, so I can imagine how you're feeling now. Hitting that cat was an accident, and you were so kind to take it to the vet. Look at it this way ... by taking it to the vet rather than just leaving it on the side of the road, you helped ease its suffering. You're a good person, garden gal, and I'm sending lots of hugs and good vibes your way.