Adam Clarke on 2 Corinthians 2:5

But, if any have caused grief - Here he seems to refer particularly to the cause of the incestuous person.

Grieved me, but in part - I cannot help thinking that the εκ μερους and απο μερους, which we render in part, and which the apostle uses so frequently in these epistles, are to be referred to the people. A part of them had acknowledged the apostle, 2Cor 1:14; and here, a part of them had given him cause of grief; and therefore he immediately adds, that I may not overcharge you all; as only a part of you has put me to pain, (viz. the transgressor, and those who had taken his part), it would be unreasonable that I should load you all, επιβαρω παντας ὑμας, with the blame which attaches to that party alone.