According to the Scriptures, the apostle Paul did not feel bad for having sent a letter to the Corinthians which he called a “severe letter”, that is, he was speaking of harsh words, but at the same time it would be the best for their salvation.
That is why Paul sends this letter to the Corinthians, since the sadness that is according to God produces total repentance for salvation, but the sadness of the world produces death and perdition.
In this letter that Paul had sent with Titus, he was worried about how the Corinthians would receive the letter and this is what happened:
For godly sorrow worketh repentance to salvation not to be repented of: but the sorrow of the world worketh death.
2 Corinthians 7:10
Titus, who was sent to carry the letter after Paul had made a visit and was sad, decided to send him a letter talking about the sadness they felt, this letter tells him about how they could go on in the Lord and not give up.
With this stern letter from Paul, he turned the sadness of the Corinthians into joy.
Beloved friends and brothers, sin leaves deep sadness in our lives, which produces death, but the sadness that is according to our God, brings repentance for salvation. Repent and you will have salvation.