hit a (raw) nerve

To evoke a strong emotional reaction, such as anger, sadness, or disgust, upon being encountered, heard, read, etc. Your column must have hit a nerve, because we are getting slammed with feedback from readers—and they're not happy. I could tell he was hitting a raw nerve when he brought up Jane's former employer and Jane went silent for a moment. Clearly, I hit a raw nerve by bringing up Dave. I'm so sorry, I truly did not know that you guys had dated.

hit/touch a (raw) ˈnerve

say something which upsets somebody because they are very sensitive about that subject: You touched a raw nerve when you talked to the manager about the need for better communications within the company.