"sometimes it does people good to have their feelings hurt".who says this and what does she say to hurt pearson?

The lines are uttered by the spirit of Mrs Fitzgerald who speaks through Mrs Pearson to her son Cyril. She tells her son that it is important to tell the truth even if it doesn't sound fair or hurts someone because one needs to face the truth. The truth was that everyone at the club called George Pearson 'Pompy-ompy Pearson' behind his back and laughed at him. Pearson did not know the truth so he would still go to the club in spite of his presence being unwelcome there. The actual Mrs Pearson had shielded this truth from her husband but as Mrs Fitzgerald realizes, Pearson would not have shown the same courtesy towards his wife. So the truth needed to be told, in the hope that if Pearson did not go to the club so often then maybe they would stop laughing at him eventually.