Praise be to Allah.
We have previously discussed the ruling on divorce issued in a state of anger, and we have stated that divorce issued in a state of extreme anger in which a person does not have control of himself does not count as such.
See the answer to question no. 22034 and 45174
Based on that, if the second, third, fourth and fifth divorces (talaaqs) were all issued by you in a state of extreme anger, they do not count as such.
The divorce that does count as such is only one, namely the first divorce that you issued when you were not angry. And you can resume life with your wife in a natural manner, whilst striving to gain self-control, and so not hasten to utter the word of divorce every time there is a difference of opinion or argument.
If a man said to his wife, “You are not my wife”, this is a kind of implicit divorce and it counts as such if he intended divorce thereby.
Bringing witnesses to witness the divorce is mustahabb because Allah, may He be exalted, says (interpretation of the meaning):
“Then when they are about to fulfil their term appointed, either take them back in a good manner or part with them in a good manner. And take for witness two just persons from among you (Muslims)”
But that is not an essential condition of the divorce being counted as such or being regarded as valid. If a man utters the word of divorce (talaaq) then his divorce counts as such, even if that divorce is not witnessed by anyone.
This has been discussed previously in the answer to question no. 119459 and 170606.