My parents always argue?

It's really complicated. They both have their own stories, but I won't bring you into that, especially since it would take up the whole page.

They cannot talk without arguing. My house has three floors, and I can hear them yelling all the way from the basement. They are incapable of having a quiet, sensible conversation.

I don't know what to do. I tense up every time they begin to raise their voices. It makes me so nervous. My dad made my mum cry once, and my mum really infuriates/upsets my dad.

No family conversations please! You don't know how many times I've tried to sit them down. They apologizes but it always starts up again in a matter of days. My mum tells me to stay out of it, and my dad tells me they're not arguing. I think i can tell when your arguing when I've been living with it for 6 years!!

I would LOVE for them to get a divorce, I'm not kidding. But they can't because of our independent business. My mum suggested it a few times, but even she knows we can't and my antisocial father wouldn't last a day without us. HELP!!!???
Im 13 btw and have a useless 16 yr old sister.
They just had an argument and it got so heated that my dad began blaming my mum, my sister and me.