I’m so sorry to hear about what you and your little snake are going through. I’m in total agreement with every bit of what you’ve already been told.
I can confirm from personal, painful experience that injuries caused by cats need medical attention. Even a healthy, well cared-for house cat harbors loads of bacteria which can cause very nasty infections. It’s happened to me more than one from my dearly loved cats. Your snake is going to “act normal” as long as/if it possibly can. In nature, being noticeably ill or injured is a great way to attract a predator. If you/your parents wait until the snake is obviously in trouble, it will be exponentially more difficult to treat and more expensive as well.
One other thing you can and should do now is to make certain that the cat isn’t anywhere near your snake. Not even in the same room as it’s enclosure, if that’s in any way practical. The cat is going to be extremely interested in the snake following this attack. Being stared at by its attacker will greatly stress the snake. Even if the snake is hidden, it will know the cat is there. This can impact its recovery. It’s also just plain awful to contemplate how the snake would feel in that situation.
Good luck to you and your snake I hope that you’re able to help it heal and that its return to good health is uneventful and quick.