Dear Yuvi, I can feel your pain from your 2nd post. Actually it is becoming tough day by day to maintain harmonious relations in marriage.
I agree with what Shribala ji has said in her post. Your situation seems to be really very difficult. Instead of breaking marriage or they both leaving the house in anger(may be your brother agree reluctantly for the sake of their child n peace in house), you all should sit together n take a decision to shift them to another place nearby so that you will always be on talking terms. Don’t let the relations get rotten due to her misbehaviour.
If you carry on with as it is then it will adversely affect the health of your parents and also on the psychology of the little child. Togetherness should not be on the cost of physical and mental health and peace.