She can file for divorce on account of the drinking habits of her husband and also the extra marital affair which eh is pursuing. It would be wise for your sister to collect proof of his extra marital affair so that she has a robust case in the court. The legal complexities have to be seen in the face of her husband's right to contest her divorce case. If he decides to contest the divorce proceedings initiated by her then it may take 2-3 years before the court decides her case.

She can file a police complaint for the threats issued by her husband. These threats constitute an additional ground of divorce.

1) save those threatening sms

2) file DV complaint against husband and seek protection order .

3) she can also seek alternative accommodation from her husband and maintenance .

file complaint in women cell of your area and along with complinant under DV act in Judicial magistrate court

1. First of all try to save the marriage,

2. let both the parties realise their their own fault first,

3. If nothing is possible then you shall have to decide whether you want to terminate this relationship or not,

4. If you decide to terminate, then she can file a police complaint u/s498A for subjecting her to cruelty for gain,

5. She can file DV case for maintenance & accomodation right,

6. He may finally approach for mutual consent divorce with compensation which may well be accepted by her.

Hi, she can file a divorce on the ground of cruelty by her husband.