Backbiting is defined by the Prophet ﷺ as "mentioning your brother in a way he dislikes," and it remains a sin even when what is said is true; if it is false, it is slander (buhtān), which is worse. Allah likens the backbiter to one who eats the flesh of his dead brother, commanding believers to shun it. Ghībah is only permitted in narrow, well-defined cases recognized by the scholars, such as reporting a wrongdoer to an authority who can stop him, seeking a fatwa, or warning someone entering a marriage or business dealing. Guarding the tongue is a mark of true faith, for the Prophet ﷺ tied belief to speaking good or staying silent.
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.