Did the third divorce occur if it was based on a misunderstanding that was later proven incorrect, and the husband uttered it to himself in a moment of anger, given the differing opinions of muftis and scholars regarding its occurrence?

If a husband divorces his wife due to a reason that is later proven to be nonexistent, the preponderant opinion is that the divorce does not take effect. So, if a man justifies his divorce with a cause, and then that cause is found to be absent, the divorce does not occur. Ibn al-Qayyim mentioned that this is the madhhab of Ahmad, and his shaykh held that it is not a condition to mention the justification verbally. Thus, if he divorces her for a stated or unstated reason, and then that reason is found to be absent, the divorce does not take effect. And whoever consults trustworthy scholars of fatwa, reliable in their knowledge and religiosity, then acting upon their fatwa suffices him, and he is not obliged to consult others.