Thankfully breaking a bone. The only time I broke one was back in the summer of 1999 on the way out to the car with my family, I think we were headed into town for something when I slipped on our porch and fell weird. As my parents supported me down to the car, out of instinct I put weight on my broken leg.
I can still remember the loss of absolutely everything else, my mind was just flooded with that agony.
Sorry to hear that. Though a broken pain must not necessarily mean severe pain. It depends on which bone you break, where and how. You got unlucky there. I had a couple of broken bones, my big toe, my hand and part of my hip (not the joint, but the Illium, which has a purely protective function), and in all those cases the pain was managable without painkillers, as long as I didn't move the injured body part at least. It was always a closed wound and there was a crack in the xray but the bone had not moved much out of place and never needed an operation. Also adrenaline played a role, I broke my hand at a Judo competition and at first just thought I just bruised, but the paramedid noticed that it moved where it shouldn't.
With all my traumatic injuries I was consoled by the fact that soon I will arrive in the hospital, will be cared for and the pain will stop.
The worst pains I had were a severe tooth ache and strong migrain attacks. It was worsened by the fact that I didn't know when the pain will end.