Need help!!

[Kit with Cat]

90 Gallon reef tank, bought a velvet nudibranch that eats planaria. Has been eating just great.

Came home, saw most of my filter feeders closed and immediately looked for my velvet nudibranch as I understand they are toxic. Looked at him, he's still moving, he still eats, but he has a large laceration to the entirety of his body.

Question is, do I remove him or let him heal in my refugium?