Chofetz Chaim Daily 18 Av 10:9 If people won’t suspect the speaker of going behind the subject’s back (eg. tzadik), then it doesn’t need to be said in front of 3 people. 10:10 Relating someone’s wrongdoing bein adam laMakom is only mutar if it’s a known aveira and you’ve seen him do it many times b’mazid.
Chofetz Chaim Daily 19 Av 10:11 If you yourself was the one that was hurt, it is asur to spread because intention isn’t l’toeles. 10:12 It’s a bigger sin to spread if he didn’t even hurt you, just didn’t do you a favor that you expected