Ozwurld,
Ohhhh, you should probably have left the nail plate in place. You may have now damaged the sterile matrix, also known as the nail bed.
The "black blood" under the nail plate was just old, coagulated blood from the injury. You had developed a hematoma from the injury, in the nail bed. Left alone, the body would have resorbed that over time. If would have gotten rid of it for you. It was the same as a bruise under the skin, the blood coagulates (causing the purple color), but the body final gets rid of it.
The sterile matrix, or nail bed, is a soft tissue, a connective tissue that holds the nail plate to the bone underneath. It is very vascular (lot of blood vessels) and also has a lot of nerve fibers in it. That is why it hurts when you mash your finger. Those nerve fibers also make the finger very sensitive, so that you can pick up a dime or very small pin. You can actually feel with your fingernail.
Hopefully, you have not permanently damaged the nail bed. If you have, your nail plate may not adhere to the bone underneath. The nail bed acts like glue. If it is damaged, it can cause a floating nail, which can be a really big problem, because patients tend to catch it on everything and rip it off all of the time.
Do not pick at the nail bed anymore. Try to keep it covered so it is not damaged any further. You may need to get a finger tip splint, to protect it from injury. Just let the new nail plate grow back in.
That will take up to 120 days for the plate to grow all the way back out to the tip. When the new nail grows in, it may have a ridge in it, but that will go away as the nail continues to grow.
If you notice that the nail plate is not sticking to the nail bed, you need to see a hand surgeon for an evaluation.
Good luck.