Harrasment by Parents & my sister

Hi,I'm harrassed by my parents to take care of my younger sister whose an adult without any disabilities.My sister is the most loved one in the house & now my parents are forcing me to take care of her financially for the rest of my life !!! My sister only wants money flowing on her all the time,and cannot hear a "No" which has been made a habbit by my parents.She loves taking small small issues to the police station & the parents fully support her.They are also in contact with a civil court lawyer whose flirtatious with her & he's planning to plot against me along with my family to some how force me to take care of my sister for the rest of my life.My father has been jobless for the past 25 years and is a stubborn person , where all what he does is to love his daughter.He sees no fault at all.My mother is a government employee and we all survive on her salary.My mother also doesnt support me much.But he's been paying for my education.Im 31 rs old and about to finish engineering after which I will be on my own.I wouldn't demand any property from my parents but my parents say to take care of an annoying, disobedient stubborn sister for the rest of my life as she's even not interested in marrying.Pls help !!! They always take help & scare me of saying that my sister is a lady,she can do anything legally on me ,file a case on me etc.In general she's been thaught by my parents that she's a female/woman and the law of land will always be on her side !!! Pls help as I'm a helpless person and feel alone in this world inspite of having a family.