Sorry you had this experience. I hit a cat once myself and was devastated. In my case the cat run off or maybe bounced off, but it was still pretty terrible.
I think you did all you could. If it would make you feel better a donation to something animal related (meow foundation, the Humane Society, etc) is a nice gesture as someone mentioned above, but it’s definitey not required or expected I don’t think. Beyond that, unfortunately there isn’t a lot you can do.
