harrasment from in laws

My marriage is a love marriage arranged with the consent of both of our parents. We have 1 girl child which is 1 year old. Initially we were staying together. Later because of my in laws harrassment, we started living seperately. Now after i gave birth to child also they are harrassing me..my father in law is a drunkard and abuses me with bad words. Many a times he has tried to hit me. My mother in law always speaks ill about my character..when we were together she used to abuse me hit me and tried to lit fire on my dress and many more harrassments. And now after i gave birth to my child she tells that child is not like my husband so its born to some other person. After 1 year of my child's birth i had been to my home..there she came and screamed all these words and tried to hit my mother also..my husband is very good person and he is the only son to them. They are hindu malayalis and am tamil christian..so my inlaws wanted me to get awat from my husband and make him to get married to a mallu girl so that they will get more jewellery. As my husband is the only son he has to yake care of them. He gives them all necessities..though they torture me. I wanted to warn them with the help of law. They doesnt listen to anyone not even to my husband..pls advice me what is the steps i have to take to saceguard my husband and my child from them. They didnt even like my child because its a girl child...my mother in law was tellibg that if she was knowing that its a girl child, she would have made something harm to the fetus itself.. Though i am a christian..we got married as per hindu culture and i stopped going to church and am bringing up my child as per hindu religion. Kindly advise.