Need clarification on this case

HI I am a 27 year old and working in a IT firm. Let me tell you my short story first. I belonged to a poor family. We were 5 members in our family. Me, my younger brother, my sister, my mother and my father. We lived in bihar. I completed my ISc from bihar and came to bangalore for higher study. due to high study cost my father had to take some loan(25000) from my uncle(Mama). We told we will give it back once we are capable of paying it. this was on 2011. But unfortunately my father passed away on 2012. my Mama also joined the cremation. He was good till then. then he went back to delhi(He stays in delhi.) So it was very hard time for us since I am the one who should take care of my family now. after some time my younger brother visited his place. When he was there he found that his wife(My mami) has affair with some one else. And she is very clever. She took all the money and ran away with her lover. my brother was there for 10 days to help out his mama. finally he came back to our native(Bihar). after couple of days mami came back to his home and told that my brohter has taken all the money and ran away. (She had to tell something to his husband in order to get in his house right?) and my fool mama believed all these. and from then he started torturing us. he would call to my mother and abuse her. he would call me and abuse me also.(Eg. sell your sister and pay my money and more I can not write here what type of word he has used.) he always asks for his money(25000). but he wont use proper word for asking his money. and our financial condition were not good because I had to complete my studies also as well as take care of my family. Now he is sending me sms(since I am not picking his call. I totally ignored him), saying i have lodged a complaint against me, my mother and my brother. and he says he will get a phone call from court.(Really?? Do we get phone call from court?) and he also threats like now he will show my true place.(Done bhai mil ke jo dhamki diya hai na. ab Police jayega tumhare ghar. Ab tumhara hasiyat pata chalega). I know he is a timid guy. he is just threatening me. What should I do? Should a lodge complaint against him. or should I just keep ignoring him? I still need couple of months to pay his money. since i am taking care of my brother who is doing B.Com, i have to take care of my sister marriage also.