My brother wife blackmail him

Hi Sir, My Brother is working as teacher and got married in the year 2012, they both happy for 5-6 months ,after she started showing her original character, we never know that she is such a cruel person, she started demanding my brother should not talk to parents, and she wants my brother must talk to only her parents.She want the control of every thing, she came from poor family , My brother thought like we are far better than her family background and he thought has given life to her ,he never expect that good opportunity what he as given become bad ,she started showing her original character, she tried to do Banamati (chatabadi) on my parents at any cost she want to kill my parents, she caught when she was discussing about her mother, and we had recorded proof, when we asked her about this , she left home went to her mother place, after 3 months she back and went to my brother school directly , where my brother is working ,and she spread bad impression over there, and the school staff did not trust her, and they did brain wash her , since they know very well about my brother kindness. she had no chance to come to home then she went to police station and narrated story against my brother, SI called my brother and my brother explained to him , what had happened. and SI told take her to home if she again doing same complaint to me. My brother agreed for that. Her attitude never changed , again she started same, she started black mail him,if he talk to him parents she will on the gas stove, take poison ..bla,bla.. And my brother is kind of person very calm and he is soft kind of person. he is struggling him self he dont want to continue life with her.. Please help us by giving best suggestion