For when we came into Macedonia, this body of ours had no rest, but we were harassed at every turn - conflicts on the outside, fears within. But God, who comforts the downcast, comforted us by the coming of Titus, and not only by his coming but also by the comfort you have given him. He told us about your longing for me, your deep sorrow, your ardent concern for me, so that my joy was greater than ever.
Even if I cause you sorrow by my letter, I do not regret it. Though I did regret it - I see that my letter hurt you, but only for a little while- yet now I am happy, not because you were made sorry, but because your sorrow led you to repentance. For you became sorrowful as God intended and so were not harmed in any way by us. Godly sorrow brings repentance that leads to salvation and leaves no regret, but worldly sorrow brings death."
Paul's effective letter
It is obvious that God led Paul to correct the Corinthians through the form of a letter. Sometimes the written word is more effective than the spoken word. Many times when I was unable to speak face to face with my husband, my children, or my friends, the written letter with more in depth thought was more effective in getting the message across without the inflection of my voice.
Paul points out that their sorrow of their wrongdoing led to their repentance.
That is Godly sorrow - offending God.
Worldly sorrow is sorry because you were caught,
which we see frequently in the news.