Feet First, First Time

I recently got my first black toenail. So I guess now I am REALLY a runner?
(side note: I did slam my finger in a door when I was about 10 and lost the nail, which never really grew back the same. It hurt really bad! This doesn't hurt at all.)
Runners do a lot of gross things and have a lot of strange and disgusting problems; snot rockets, rubbing Vaseline in weird places, spitting, bleeding nipples, blisters, chafing, peeing in public (or worse), dirt, grime and talking about bodily functions are the the norm in a runner's life.
I've been lucky. I seem to have avoided many of the major issues up until now, including the black toenail syndrome. I hear runners talk about them all the time, and according to some articles, if you have ever run a marathon or a hilly race, you have probably had one. However, I never had before. Until now. I noticed it about a month ago and since then, half of it has separated from the nail bed. The problem is, only half of it is black. The other half is perfectly fine.
I have a 50k this weekend and half of my toenail is hanging off. I am not sure whether to cut off the bad half and have half of an exposed toe or to just leave it and hope the bad  half hangs on for the whole race. So I started Googling. Of course.
Did you know there is a way to tie your shoes to prevent black toenails?
Jeff Galloway says that the reason we get them from wearing a too tight pair of shoes, having too fast of a mileage increase, or running in excessive heat or hot weather.
Here is how to prevent them. And if you are really brave, you can watch videos on how to remove them. I am not really brave. I only watched about 2.54 seconds of it.
But the best thing I found while trolling around the web was this article, which talks about people (including Marshall Ulrich) who have had so many issues with the black toenail that they just had all their toenails removed. For good.
However, I am not about to remove all of my toenails. And I am definitely not doing what the guy in the video did (hint, he used a knife). I might try the shoe tying trick. But I need your help; I don't know what to do. Do I leave it and run or cut it and run?
Have you ever had a toenail or a fingernail fall off? How did it happen? Did you remove it or wait for it to fall off?