How to proceed with divorce

Dear sir, My brother got married on 5th nov 2012, but since then, my brother, my parents have been troubled a lot. From the first day of marriage, she is reluctant to stay with my parents, but my brother is the only son and he insists on staying with them though my parents can manage on their own. I had a miscarriage at 7th month and came to my parent's home for medical treatment, even that has been a problem for her. She and her parents want me to leave asap. Infact they don't want me to come. Right from the beginning, she and her parents have been making false accusations (we don't give proper food to her, my mother ill treats her, she feeds wrong things to my brother about his wife etc) on us and defaming us. When she came back from her native place for the first time, she has had a suspicious attiude as if she is trying to perform black magic which scared my brother off. She has been secretly speaking over the phone with some one late in the night. It was after 3 months of marriage, until then my brother had a nice relation with her inspite of her various behaviour problems. From then onwards he refused to have physical relation with her. We tried to reconcile things between them but of no use. Now those people are blaming my brother of impotency and that they didnt have physical contact even once and that my mother is responsible for everything though that's not at all the case. My brother now doesnt want her in his life because of all this. Those people are torturing us everyday stating that if my brother divorces her by talaaq, then they would file a police complaint. They want my brother to live with the girl forcefully on their conditions and defaming my parents. This girl is the daughter of my father-in-law's own younger brother. My father-in-law dislikes my parents from the beginning coz they couldn't give the dowry amount they had promised.So, he has joined the fight against my parents and troubling my marital life by feeding wrong things to my husband. Our relationship is not that bad they we need a divorce.Another point to be noted is that, the girl was actually a minor 17 yrs when they got her married. They hid the actual age from us, its after wedding that we got to know. In the urdu nikah nama , her actual minor age is mentioned whereas in the school certificate where she studied upto 6th standard, it is quoted that she is a major. Using that school certificate, her father obtained a marriage certificate where her age was that of a major. So, there is a disparity in the urdu nikah nama and the english marriage certificate. If not by the legal way, then they are planning to extort big money from us with no mistake on our part. My brother is a central govt employee and he is in the probation period until the next few months. Please help us.