We had a cat that was hit by a car (35 years ago) and had a broken pelvis. I can't remember what the vet did but I do remember that part of the treatment was that he had to stay at the hospital.
We had small children at that time and we could not afford it. So we took him home put him in a crate in my daughters bedroom. And took care of him. He lived for another 10 years and his leg healed ok. I know it depends on the break, but you probably have to find out what to do exactly.