Is it ok to feel happy when the one who hurt you gets hurt?

When one who has hurt us gets hurt, foolish and scoffing voices cheer us on. “Hover over your fallen enemy! Fist-thump your chest and boot-heal theirs! Your sentences are saws. Go slow with the cutting!” Naïve wisdom shudders. “No, no, we have no enemies” it urges us. “All is well!”

The wise say “no” to both ways. But Why?