I think you have answered your question in the topic in your opening lines. Nothing good comes out from making decisions in a state of anger because it would not come out right, it will only cause regret.
Emotions can run wild and as such when it's not under proper check, you can say things or do things. Words are things that can't be taken back once said, if it is a bad thing, it has done the damage. So imagine it concerns a decision making that was done under the influence of anger, it won't end well.