What is the ruling on divulging people's sins and threatening them with exposure, even if they have repented of them, or committed them in their youth before reaching accountability, or were unable to control themselves?

Concealing the sins of a disobedient Muslim is obligatory or strongly recommended. As for shaming a repentant person for their sin, or divulging their secret, or threatening to do so, that is forbidden. Whoever committed a sin before puberty or was in a state of compulsion due to inability to restrain themselves from the act, they are not held accountable for it. Shaming a repentant person or threatening to expose them is among the sins that indicate the baseness and ill-manners of the perpetrator. Such a person must be advised and the حرمة (prohibition) of their actions must be explained to them.