Calm down, don't worry.

Cresties drop their tails so easily, it's almost expected.
Just make sure that it doesn't get infected. No need to put anything on it, specially ointments. Let it dry out and scab over. If you see dirt on it, maybe lightly mist it off. As long as it's clean, it will heal in no time.
Unfortunately, the tail won't grow back. Cresties get one tail, that's it, no regrowth.