I'm so sorry this happened to you and your featherbaby.

Don't beat yourself up over it, as accidents happen, and nothing can prevent them all the time. We all, when we raise chickens, eventually have to deal with an accident at some time. I know you feel awful about it, and you have the right to mourn, but chickens occasionally come out on the other side of terrible injury and survive to live a long and happy life.
You've gotten the best advice possible under the circumstances here. The only advice I can add is hydration. If she will take any fluids, and if you have any vitamin/electrolyte mix (Durvet sells it in a jar with a scoop for measuring, very handy), or even Pedialyte or Gatorade, I would offer the vitamin mix in water or a half water-half Pedialyte/Gatorade blend, preferably with a syringe (no needle) or dropper dripped at the edge of her beak, were it leaks into the beak, and she will hopefully instinctively swallow it. Keeping her hydrated at this point is the biggest hurdle.
It sounds like she has incurred a skull fracture, or possibly a closed head trauma - the main sympton being the blood from the nare (nostril) leads me to think that. What will happen now is that the brain will swell somewhat due to the injury; how much is unknown, as every brain injury is different, as is every reaction to one, even in humans. It's possible the brain will swell so much that there will be worse injury to it, and she will simply go to sleep and not wake up. There may be physiological symptoms like twitching or seizures during the swelling process, too.
At some point, if she survives the period of swelling, it will go back down. As long as she remains hydrated, once the swelling goes down and the brain returns to normal size, she could easily start getting up and acting completely normally, or she could end up with some sort of disability, but that's completely impossible to predict. As long as she remains able to swallow the liquids you dribble in the side of her beak, the outlook, while poor, is still not certain.

I wish you all the luck in the world with her! I know the feelings you're dealing with right now. Just hang in there, and remember to not hold yourself responsible for what was a fluke, an accident you could not control.
