Illness/Sickness: Young Axolotl's leg is cut off/broken?

Hello!
I am a new axolotl owner and have had a pair of axolotls since they only had nubs for front legs. They have been growing excellently, but today while preparing to move them to an actual aquarium vs. the big plastic storage boxes I had them in, I scooped the leucistic one and noticed that her leg was...broken? Or half bitten off. I got some bad pictures, but you can sort of get the gist of it.


You can see how it's backwards, and in the picture with the red bottom you can see a skinny section that I think is bone. The "hand" is discouloured, and it gives me the idea it's been like this for a day or so. I think it may be because the other axolotl got too close and bit the leg, since they tend to crowd together when they see the pipette coming out. Should I now separate the siblings (they are the same size, btw)? I heard somewhere I should try and cut off the hand, but that seems like if I missed it would just cause a lot of stress (especially seeing as they're only like two inches now), should I do that? Is there anything I should add to speed up recovery?
Thank you so much!

Don't ever self-amputate. For other problems like this on the forum most people say take it to the vets.

They are great healers but if it is still connected and bone is broken it may be rather difficult and messy to regenerate.

Oh thank goodness, I don't want to have to cut off limbs.
Is there a certain point I should take them to the vet, i.e. appearance of weird growth/fungus, no regeneration after a few weeks, axolotl not eating, etc, or would it be wiser to just see if it heals itself? As is, he seems just fine and is swimming and eating well.

I meant in my last post it might be difficult to heal if it's still attached with a broken bone and broken skin. I would take it to the vets to get a vets opinion.