She corroded the environment of my HOME. Please help me?

Send her home to her Mother. Your own Mother has a right to be respected in her own home.Keep your brother's child with you. You and your wife chip in to pay a housekeeper and let Grandma supervise and help care for the child. Or let your brother take them both our of your parents house.But he must stop beating her. It's wrong and won't do any good anyway. And the child should not see that. Your parents are getting older and do not need all this stress and anxiety. One way or the other, the sister-in-law has to go.