I am not recommending. I am an equal victim here. But thats the eventual course this "brother" would take and any inhuman lawyer would suggest.
Even courts are entertaining 498A on grounds of not picking call from wife, mental torture. The system is rigged and corrupt to the core.
I suggest the husband write a will and commit suicide. The choice for him now lies in
1. continuing life with a deranged woman who by own brothers confession is harrassing in-laws. This is like a knife hanging on him since God alone know when the woman will feel scorned and insulted.
2. Not continuing life with her but putting parents life and mental well being at risk
3.Apply for divorce and face and fight all consequences. This will take decades if wife is not willing.
God bless all