HELP! Exposed bone??

I have two axolotls currently in my tank, one named Falkcor and another, Cilantro. A whole fiasco happened with Falkcor a little while back if anyone remembers, she fell out of her tank and had to get a limb amputated. Anyway, she is back to normal and has been introduced back into Cilantro's tank a few weeks back. Everything was going fine, they'd be around each other with no conflict, they eat together, everything's been normal as it used to be.

Two days ago, I noticed Cilantro's tail not looking too fresh. I've had them for over a year, I've seen their tails get nipped before by each other on accident, but Cilantro's tail had a whole chunk out. Today I look and it looks worse, like it got bit again. It's ripped at the tip a considerable amount, red from blood, and I can see his tail bone. The tip of his tail bone seems to have been ripped off with the rest of the tail, and I can see the rest of the bone through the wound.

What do I do?? Do I go about making a divider for them, or put him into the fridge asap?

Update: I'm putting him in the fridge because I'm scared something bad will come out of waiting for a response beforehand. If fridging is the wrong option, let me know and I will start to take him out tomorrow. Also, there is something on the tip of his tail, I can't get a good photograph but it looks like it could either be fungus or dead skin. Should I do salt baths?

It should heal on it's own to my understanding. You just have to watch for infection.

I would permanently separate the two axolotls.

I agree with Katie, it might be best to keep them separated. How many hides do you have, and how much/often are you feeding? And how big is your tank? f you want to keep them together you may need to add more hides and feed them more, that's usually what they fight about.
As Katie said it should heal fine on it's own, keep Cilantro in a tub with cool clean water (daily changes), or in a second cycled tank.