Hilchos Lashon Hara, chapter 2, section 11
If the seven leaders of a town sit down for a deliberation and came to a majority decision, it is forbidden for one of them who opposed the decision to tell anyone that he had the opposite opinion throughout, but that his fellows disagreed with him and decided against his opinion, since this would be lashon hara.
This is forbidden not only in a case where they decided not to tell others what happened at the discussion, but it also forbidden even to merely say this by hint in a way the listener understands of himself that his opinion differed from the other town leaders.
It makes no difference if he related this of his own volition, or if someone cursed and insulted him because of the decision. In every case, it is forbidden to talk.