For even if I made you grieve with my letter, I do not regret it—though I did regret it, for I see that that letter grieved you, though only for a while. 9 As it is, I rejoice, not because you were grieved, but because you were grieved into repenting. For you felt a godly grief, so that you suffered no loss through us. ESVUK

 I know I distressed you greatly with my letter. Although I felt awful at the time, I don’t feel at all bad now that I see how it turned out. The letter upset you, but only for a while. Now I’m glad—not that you were upset, but that you were jarred into turning things around. You let the distress bring you to God, not drive you from him. The result was all gain, no loss. The Message

Why do we discipline our children when it hurts us so much? Because we know it is for their good. So we are prepared to absorb the pain if only we can get them back on track and lead them in the right direction.

Endure hardship as discipline; God is treating you as his children. For what children are not disciplined by their father? 8 If you are not disciplined—and everyone undergoes discipline—then you are not legitimate, not true sons and daughters at all. 9 Moreover, we have all had human fathers who disciplined us and we respected them for it. How much more should we submit to the Father of spirits and live! 10 They disciplined us for a little while as they thought best; but God disciplines us for our good, in order that we may share in his holiness. 11 No discipline seems pleasant at the time, but painful. Later on, however, it produces a harvest of righteousness and peace for those who have been trained by it. Hebrews 12:7-11.

Of course, the application of discipline will reveal what is in the heart. Will there be genuine contrition and repentance, or superficial remorse?

Maybe only time will tell.

But Paul could rejoice that the Corinthians had responded well with godly sorrow that leads to repentance.