My Parents fight constantly what should i do?

Okay well today my parents got into a argument they went out side and i could hear my dad yelling at my mom then i hear my mom scream i wanted to go out there so bad and just knock my dad out he always says i would never hit a girl/woman nut i know he hit my mom but any-hoo when there fighting what should i do leave or just stay and listen to him abuse her all the time? If you chicks and dudes can help me please i would really appreciate it thanx : /