Scared of becoming hateful

This is to the people here that don't play the game "whoever's chronic pain is the worst is the most deserving of care". How do you keep your personality from changing?

I can feel rage rising up inside me whenever I am faced with someone who wants to compare pain or illness and then that makes me go into defence mode and then I become the thing I hate. I am usually very understanding. Even when people are short with me or slightly rude. I let things go. I used to have a sort of mantra that was "I don't know what their morning looked like" and maybe I would be in the same mood if I had the same morning as them. This doesn't work anymore for me. I'm not sure if it's because I'm finally fed up that I never receive it back or if that living with pain 24/7 has changed my personality? Does anyone else feel this way? Help, i'm worried this is how you become a Karen.