you're not to blame. my parents are the same. it sounds like your dad is the one to blame. he has anger issues and a habit of taking emotions out on your mother. i really feel for you because my house is the same. i do not speak to my dad and my mom has autoimmune health problems because of the stress.

the only thing i can advise is for you to help around the house and be there for your mom and brother. i would say try and confront your dad but like mine, he seems like a lost cause.