The severest punishment suffered by a sensitive mind, for injury inflicted upon another, is the consciousness of having done it.

For anyone with a conscience, no outside penalty matches simply knowing what you did. Nobody has to impose it, nobody can lift it, and it arrives at odd hours for years. That is also why people who have hurt someone often want punishment: an external sentence feels finite, while the knowing does not.

If something you did still sits with you, the way through is not more self-reproach, which only deepens the groove. Say it plainly to the person if that would help them rather than you, make what repair is available, and then let changed conduct do the rest of the work.