Halacha 1: Rechilus is an issue whether spoken to an individual or in a group. Don’t make an excuse that if I am willing to say what someone else did or said about someone to a group and they will hear what happened so it like saying it in there face it is now permissible. It’s not permissible, or appreciated.
Halacha 2: Avak rechilus, where a statement could be taken in two ways, positive or negative is also forbidden to say in cases where it is taken negatively. Examples will be discussed in more detail in chapter 8. But certainly if you try giving it a negative slant it is forbidden, but even if you try giving a positive slant but you know the people you are talking to will take it negatively wither because the person talked about they have a previous history if no liking, or the listeners themselves knowingly have a predisposition of always thinking negatively so whatever they here they will just take it negatively then you can’t tell them even if you try to give a positive spin. It is in fact transgressing the sin of placing a stumbling block in front if the blind by telling avak lashon hara to such people who are called a nargan in Hebrew.
If the way the sentence was said was pareve, meaning no slant negative or positive and the people listening would not automatically judge negatively then it might be possible to say it definitely if it’s more possible for the listener to judge favorably like in the case of Bava Kamma 99b where a guy gave a butcher a cow and Rav poskined the meat is treif and the butcher doesn’t have to compensate the owner. Rav Kahana and Rav Elazar bumped into the owner and told him that Rav did two things for you. That was all they said, that could be negative or positive. The gemara questioned how they can say this if it’s negative and you can’t tell the litigant what the judges decided because it’s rechilus. Rather those word could be taken positively that, for one thing Rav stopped you from possibly eating something prohibitive. Since there line could be taken in a positive light and the owner had no reason to think otherwise, especially since Rav was known to be an honest and trusted sage that is why they were able to say what they said. However it might be only in a situation like this where there is more of a reason to judge favorably since Rav is a trusted sage but in general one has to be very careful when making pareve statements if they can be said at all, to avoid them being taken the wrong way. It also might be dependent on whether you are willing to say this statement of avak rechilus in front of the person you said say it or did. If you are not embarrassed to repeat what you heard or saw from him then you can say it if not you are forbidden to say it to anyone else.