Is the measure of injustice (maẓlamah) determined by the psychological pain and sorrow resulting from the act, or by the act itself only, and should one mention the lie when seeking forgiveness or not?

Lying is one of the most heinous sins, and repentance from it involves abandoning it, regretting it, and resolving never to return to it. If the lying caused harm to another, the liar must seek absolution by asking for forgiveness from the one who was harmed, unless doing so would lead to a greater mischief. It is not a condition to inform the one who was lied to that one lied; rather, an apology and a request for forgiveness suffice.