How to deal with the harassment caused by my uncle and his wife?

My grandfather has two sons and one daughter. My father, the elder one and my uncle built a one storried house jointly under both their names legally. Then my father married and settled in that house with whole family- my grandparents, my parents and my uncle. My uncle said he had no plan to marry then so the house was created such a way that it cannot be separated into two halves. We lived quite happily. Decades later our grandfather passed. After few years , my uncle brought a stranger woman to home and did a civil marraige. Afterwards that woman whom we know nothing where he came from started living in our house and we didnt oppose. But slowly she began to show her nature, as a result feud took off my parents and me separated from the joint family. My father built half of the second storrey by his own and gave up most of the first floor. Only kept his room and used the first floor for only daily unavoidable needs like passage, bathroom. One room was used by my grandmother. And the third one was taken by my uncle's. After my grandmother s death , her room was kept joint as there was house gods and her antique furnitures. Now my uncle and her wife are harassing us in every possible way so that we give up ussage to the bathroom , grandmother's room. I bilieve my uncle's wife is very dangerous and can do many bad works to threaten or to make us in fall in her bad plan.