my elder sis won't let me study....

hey yall. I am in class 10th
As you all know, board exams are going on and the next exam is on 25th, sst.
I was casually studying then suddenly my elder sis started to scroll instagram reels. My mom said to her that she should lower down the volume. Then she called me a kutta(an abusive word in hindi) and ignored my mom. Then i came to her and requested her once again but she didn't listen. Eventually i shifted to my room but the fact she didn't even consider my exams is not okay.
Also, she has some mental issues and rn she's not in a good mental state