1) your brother can file for divorce on grounds of mental cruelty
2) wife calling husband impotent amounts to mental cruelty and is ground for divorce
3) wife abusing mother in law amounts to mental cruelty and is ground for divorce
4) in case wufevfukes case of dowry harassment apply for and obtain stay against arrest from HC
5) Police would issue your brother and other family members notice to record their statement
6) in alternative brother should stay separate in re nted flat with his wife