When will it get okay??

My sister is having abusive behaviour and which always cause conflicts and chaos In house. She is so abusive at one moment and next moment she behave like she said nothing. Her behaviour always cause chaos in house because of that being at home on weekends feel so stressful. I don't know is this only her fault or others also. But this is affecting my mental health and elder sisters too. She is also at home and studying for competitive exam to get job but she ( younger sister) is abusive to her because she is most of the time in day is studying for her. In the morning it always chaos at home and after some hours it is like nothing happened here. If someone else would do this kind of things to me I would ignore them but she is my sister and I don't want her to do this at home. Sometimes I worry about her what will happen to her after marriage because of her behaviour. In my surroundings I see a lot of girls getting divorce because of this.

I don't know what is wrong with her, is this my parents fault that they didn't give her enough love in childhood that she became this bitter ?? Or is this because she is struggling with her own issues. She did completed her post graduation last year. But sometimes she behaves like Teenager. I don't know what she wants. I am am her younger brother and in my family there is only dad who earn money so it is really hard for my dad to provide her more money to study as we all are dependent on our dad for money. So I wonder about her a lot sometimes. I have a lot of problems in my life and this is also causing me stress. Sometimes I think about moving abroad to study so that I don't have this kind of problems and also maybe I will be able to provide my family some money. But there are so many problems and I don't know what to do. there are so many things going in the life and I don't if this ever gonna be okay or not. Or I will spend my life with these problems, trying to solve everything and ending up being depressed person in family. Not living life really like i want.