You do not need the last word when you already have the lesson.

The urge to be conclusively right in a disagreement is an urge for a feeling, and it is separate from having actually understood the situation. Once you know what happened and what you will do differently, the exchange has already given you everything of value. Pursuing the last word usually re-opens something that had finished. It also tells the other person exactly how much they got to you.

When you are composing a final reply, ask what it adds beyond satisfaction. If the answer is nothing, keep the understanding and close the conversation. You will notice how quickly the urge fades once it is not fed.