Shemiras Halashon Halachos
Hilchos Rechilus, chapter 2, section 3 Some say that if a person denigrated someone before three people, there is no more rechilus involved in speaking of the how he denigrated the person [because the news will spread anyway]. This needs all the requirements mentioned earlier in paragraph 14 in laws of lashon
hora. But one may not rely on this leniency in practice because many Rishonim disagree with it and forbid speaking to anyone if one's intent is to spread the story, and certainly not to the person spoken of. Even if one has no intent to spread the story one should still not repeat the story as we wrote above in laws of lashon hora paragraph 11.
Hilchos Rechilus, chapter 2 , section 4 According to this, if a partner wanted to do a certain deal without his partner because he thought others would join him in the deal but in the end they did not, or similar cases, one may not reveal this to the other partner even if the matter was already said in front of three people,
because the other partner will certainly resent it.