My sister doesn't want to give divorce, she like to continue her life and file the FIR to husband

Dear sir/madam; My sister got married on 2018 and they are always small small fight and stayed in native home various days(first time 15days, second fight 1month, after fight 3months, next fight 5months, now she is stayed her parent home almost 10months ago). Because husband mother and sister is given torture to her, and this four year husband use his influence and given the fake complaint at police station. Now he send divorce notice. But my sister is like to continue this life, she expect he will change his character. Still he is listened his mother words. Currently, wife is noticed his character and she have a evidence for his mobile recorder. From marriage, he will record her family member call and doubt about her character. But she is good and her family is well reputation family. But from beginning, husband and his mother and sister given a torture; mentally torture, her family reputation spoiled, physical torture, fake complaints, sometime asked money torture, always doubt and cruelity. Currently he sent the divorce notice, so wife can file the FIR complaint against to husband to police station. Please advise. Thanks.