For the kind of sorrow God wants us to experience leads us away from sin and results in salvation. There’s no regret for that kind of sorrow. But worldly sorrow, which lacks repentance, results in spiritual death.
Just see what this godly sorrow produced in you! Such earnestness, such concern to clear yourselves, such indignation, such alarm, such longing to see me, such zeal, and such a readiness to punish wrong. You showed that you have done everything necessary to make things right.