Wife and Cousin

i have a cousin sister whom for whom I have very much affection. My parents are against her and claim an illegal relationship between us. After my marriage I explained the same to my wife and she is ready to accept her. So, I took my cousin to my home and she was there for around 9 months. After that when I asked my wife she said that I didn't find any such relation between you both. Later due to some personal issues, she now claims that we have a illegal relation and wants her to be away from my life. But she assured me and my cousin lot of times that she won't disclose this to anybody. She already disclosed this once and she said she is guilty for that. So, I started to invite my cousin again to my home. But now she came against me and claims an illegal relationship between me and my cousin. My concern is that I have trusted my wife blindly and she exposed my infront of everybody in a negative way. I don't want her any more but now she threatens me of filing a case against my cousin. I don't want to let my cousin in trouble but want to get rid of my stupid wife. Please advise me.