Request for Help pertaining to mentioned question.

I have 1000 questions on my list. This is one of them.Since my childhood i am seeing my father times he is right in his decision and at times he is totally out of control.My parents got married on 18/04/1982. My father date of birth is 30/10/1959 , my mothers date of birth is 09/03/1966. I have seen my mother being abused physically , emotionally and psychologically 6 to 7 times for this very particular reason. My father is upset that his In Laws cheated him saying that my mother was born in 1966 (true) where as per my father its 1960(Assumption). I am not sure whether my father has lost it or don't know. When ever some one asks my mother when she was born she totally has lost it and started saying she was born in 1960 rather than 1966 otherwise its again the same old routine of abusing....I am worried about my mother at he age of 50 why in the gods name is this happening.... Can anyone explain what can be done. How far is it right that after 35 years of their marriage still my dad abuses my mom.??? This is not the only example as i said i have many.. I have seen my mother for days weeping for silly reasons my dad fight which are very useless. Can anybody help me what to do.. Me writing this here is the right to fight for my mother or looking for answers i don't know.