about forgiveness

I recently listened to a philosophy professor talk about pain. The most important part he said was this =

"the part of the pain you imagine in your mind will cause you more pain than the pain itself. "

Please examine the striking part I mentioned carefully, it is very important. What he really means is that if someone treats you badly, the part that makes you sad is the part. It's not about being treated badly, it's about the thoughts you have in your mind about the bad behavior you've been exposed to.
Now I will give an example, Ahmet insulted Irem because Irem showed a behavior that Ahmet did not like but she was not aware of it, Irem could not understand this insult but she was upset because she was insulted. After a while, Irem thought about the incident again and again and tried to make sense of it, then she remembered that she was insulted and became even more sad. She couldn't see a way out, or the only way she saw was not to see Ahmet until he apologized. Either way, Irem will relive this insult in her mind again and again and Irem will suffer. So, what was the real pain for Irem? Is it the insult itself or the thoughts she has in her mind? Preventing this is by learning to forgive, so you can actually choose the best option for yourself.