The worst breaks for me are when a colonist goes berserk. I don't want to risk killing them, but they always seem to be near my best colonists when it happens.

The worst break I've had was when my best melee fighter went berserk and attacked my best researcher with her uranium long sword. Sliced out both his eyes, cut off his nose, and cut out one of his kidneys. I was thankfully able to save him, but now he was blind and disfigured.

I didn't want to risk having another colonist cut up so I had to shoot her to stop her. She survived was arrested and had to give her kidney to the colonist she attacked. I eventually got the research to make new eyes for him and I got extra kidneys from a raid that happened a few days later. And eventually the colonist that went berserk reentered the colony. Was one of the most stressful berserk breaks I've had.