Does the husband's statement, "That's it, it's final," constitute a divorce, after the wife thought he had said to her, "You are divorced," when he had not said it?

The divorce does not occur with the mentioned phrase. It appears that the husband intended that if he were to utter the word divorce, it would take effect, but he did not actually utter it. Rather, the wife was mistaken about that. Therefore, there is no divorce.