Chofetz Chaim חפץ חיים

And now, see, my brother, how much great judgment he requires to determine in what manner to tell the story. For while he is speaking he stands in great danger of [transgressing] the issur of speaking lashon hara if he does not guard himself [to satisfy] all the conditions, especially II and IV. And it is apparent that about this we can say (Mishlei 18:21): "Death and life are in the hand of the tongue." And if he does not take counsel with himself before he starts speaking, how to express this, he certainly will fail, G–d forbid. For at the time [of speaking] the power of anger intensifies itself in a man, and it is impossible to prevent this. Therefore, he must be extremely careful to take counsel with himself before speaking, how to utter what he has to say, not to aggrandize the wrong beyond what it is, and to intend "benefit" alone, as we have written in section thirteen.