Does a divorce uttered by the husband while in a state of extreme anger count, when he did not intend the divorce, and he linked it to a condition (the wife attending the wedding) that was not fulfilled due to compelling circumstances beyond her control, knowing that when he uttered the divorce, he thought she was making excuses, but it later became clear that she was truthful?

If the situation is as you described—that you uttered the divorce (talaq) while not in full awareness due to extreme anger, to the extent that you did not recall what you said until those present reminded you—then this divorce does not take effect.

Shaykh Ibn Baz clarified that divorce pronounced during extreme anger does not take effect if it deprives a person of their awareness, to the point that they do not know what transpired from them, similar to someone who is insane or an blameless inebriated person.

Similarly, if a man divorces his wife based on information that later proves to be untrue, the divorce does not take effect.

Therefore, if the matter is as you described, your divorce did not take effect.