Father in law occupied house after death of wife

me and my wife built a house in tirunelveli. iregistard that home in my wife name.i even got loan in her name to build house. after building completed, it was unfortunate thing happend that my wife died in accident. Then i brought my father in law and mother in law to take care of my children.Everything was going well. THeni decided to get marry. My FIL opposed it. then i got married inspite of opposing.Now FIL refuses to go out of my home by saying that it is there daughters property, also making my two sons to oppose me by by brain washing them. I complained to police but they are not taking action on them instead they are threatening that they will file FIR against me if i trouble my FIL . what should i do to get them rid of my home. They got hold of all the door keys and they are locking the home when they go out and i am unable the go inside my home.they are even complaining againt me in polce station that i shouldnt enter that house in their absence . Inspector also threatened me. What should I do?