having an extra marital affair

hi I'm asking this on behalf of my aunt, She's 58 now and in the marriage for 38 years, her husband working in Central railway is having an affair in his office of Central railway, my aunt was informed by that lady's in-laws they came to our house and informed about their affair from past 5y and asked us to tell our uncle to stop this when we tried to follow we came to know that he has even bought a house on rent for her with her kids who r 20y & above they call him father even though they are not born to him. and but that lady Denise to leave him along with her kids she's a widow, but my aunties life is getting destroyed at this age, he even hits her & abuses her & told her he will throw her out, not even let her get his pension or give her any allowance, she's a high diabetic & blood pressure and skin dessise, she's completely dependent on him and his this affair is takeing a toll on my aunt and she's falling more sick,now what all we can do as Nessesary legal action at the jurisdiction and his office cos he is a government employee and the lawyer she hired is just making her go round & round, what all charges can be pressed against him, what is the law where can we find it, just help us we need despret help