Keep a friend’s secret even after the friendship ends. That’s how you know it was loyalty, not convenience.

Loyalty gets tested after the relationship is over. While you are still friends, keeping a secret costs nothing, and the proof arrives later, when telling it would get you sympathy or a laugh and you choose not to anyway. A confidence was given to a person rather than to a friendship, and the person is still you.

If a friendship has ended badly, decide now what you will do with what you know, before you are tired or hurt and somebody asks. The answer that holds up is nothing at all. People who notice that you never told will trust you with things for the rest of your life.