Mental Harrasment by wife

I ma married from last 3 years and have one daughter of 18 months i am facing mental pressure from my wife for staying away from my parents where i am the only son and my parents are dependent on me. I have sister who is married n at present she has come here for delivery. I stay in karnataka Belgaum. Her parents call her up regularly an after every 3 months they start calling her to come to thier place an she start troubling me an wen i send her to her parents after 15-20 days she calls an tell i will never come back near me an start complaining abt my parents n sister dat they trouble her etc which are clearly lies. Her relatives threaten us to complain in police or try to pressurise us dat we have 100 ppl we will see u etcc. I am facing all this from 3 yrs rite after marriage. Its same after my marriage. Now one month back she went to her parents place an sent letter from mahila police to come to police station. I dont kno nor it was mentioned in letter what she has complained abt. Please advice what i must do an help me out to get out of this mental torture.