Scared of parents fighting?

I’m a young teenage girl living in a family where my parents are fighting a lot. Not fist fight but verbal fight, and it affects me emotionally and physically. They argue twice a week, and sometimes they make it big and end up going totally crazy on each other. I’m always trying to stop them, by reminding them of me. They don’t really seem to care, but I believe they do. Or else they would not be together today. My dad used to tell me he’ll do anything to keep this family together for my brothers and me. My dad is sick,cancer but he got some treatment many years ago. He can’t work anymore. My mum is always stressing about everything, she keep complaining about her life because she’s the one working and my dad is not. Of course he would if he could. I don’t understand my mum sometimes. 3 years ago I started to work for my mum. I helped her out, because I knew how hard it was. I didn’t get the same childhood as every other kids. I went to school everyday and work afterwards. I didn’t have time to be social after school. I never complain because it is all for my family. Can anybody help me? I don’t know how to deal with it, when they fight. I always do my best, how come they are like this all the time? They can see how I cry and beg them to stop when they fight