Cali should come first. Cali didn't bite you intentionally, She was in a war with Nala and she wasn't paying attention to what you were doing nor even realize she bite you and not Nala.

So rehoming Nala would be the best solution and Nala might very well now also be a Dog that should the only dog in a home.

Do you know of someone that could take Nala now so you have time to find her a wonderful safe home? Or check with your local pit bull rescue, explain the situation and see if they can possible board her while you find a that home she deserves.

Please do be upfront with anyone interested in adopting Nala that she and Cali fought and it has been ugly. They need to know the history so they don't bring home a puppy and Nala feel threatened and starts fighting due to the trauma she is going through atm.

Do take extra care to make sure you have her under complete control while you out, often once a dog is pushed to fighting she may feel she will have to continue to fight for your attention. this is true of all breeds not just pitbulls.

Im sorry you have to make a tough decision