At work, a colleague and I accidentally offended her because of a joke. She was very unhappy and spoke ill of me behind my back all day. How can I fight back?

The best way to fight back is to ignore it! Don't be too gentlemanly with villains, or they will become more and more arrogant. The more you explain these gossip, the worse the situation will be, so ignore it, ignore it and follow your own pace of life as usual. Don't let other people's attitudes affect you. With this, you win!