Mental Harrasment by my father to my mother

Hello From past 8 months my dad is mental harassing my mom because he thinks that she has an extra Martial affair. This person was only a friend of my mother which my dad used to compare him to my mom. Now the case is I've a younger brother studying in 9th standard. My mother is fed up of all the dramas and threats which he's giving. He is threatening us that he'll kill us in some or the other way. The people who are supporting him are my mother's relatives and they're doing this for the property sake. I've completed 18 and I'm the elder daughter who is studying out of town. All of sudden my dad has stopped giving me money for the expenditures and further he doesn't wants to look for his children's education. If I apply for Maintainance, in how many days I would get it? And my brother is a minor child, in what span of days he'll get the maintenance? And can my mother apply for a case of not allowing him home because he is torturing and a threat for us? Because she earns less than my father, my father is a govt servant. Is it possible?? Because they are not yet divorced! Please help asap!