I'm sorry this is happening and I understand how upsetting this must be for you and your brother. I remember as a kid, my mother had a BF who visited on weekends - my father died when I was 2. Anyways they used to fight and I remember crying in the bathroom and covering my ears....wishing it would stop.

I wonder how surprised your parents would be if, you called the police anonymously or taped their fighting and let them hear themselves. Can you tell them when things settle down, how upset this makes you?? Good for you for not running away - this is their problem but they need to know this makes you and your sibling feel awful. Hugs to you.