Harassment from husband and in lawS

Hello.. My sister is married for 20 years n has two kids.. A daughter aged 18 and a son aged 11. It was a love cum arranged and they r relatives.. From time she was married not one day she had peace.her husband in laws tortured her constantly. She tried committing suicide after her first baby was born. Luckily she Was saved. Her husband doesn't treat her like wife, abuses her all the time. She has tried by all means hoping he would change one day but it dint happen..may she decided to cm back but due to my parents non supportive nature n relatives pressure she had to go back.. She once tried committing suicide a year back and was ther in ICU for several days. They dint even inform us abt it. She decided to cm n started working buy again his relatives took her back pressurizing her and usual my parents dint say anything, inspite of her husband telling he doenst need her. Her in laws feels she should tolerate her daughter gets married. The torture continues she is terribly depressed.they don't let her out n locked her up, once smhow she escaped and came back home but they took her back forcibly. I want to help her and she al alone. My family is not supportive as they more bothered their prestige. But I fear she might take extreme step again cz she is totally depressed. I want to help her and take he out of this hell. Pls help:(