Divorce / Anullment due to Fraud

Hi Experts, I am here to seek advice on the unfortunate event of my separation with my wife (not legally yet). Following are the facts for your quick reference, its a long story actually so you might have to spend a couple of minutes:- We use to work together for 3 years in the same company & then we got married on April 15th,2012. Before marriage, my wife told me that she had a tumor in her thyroid during childhood & she was operated for the same after which she has been absolutely healthy from last 12 years. She requested me to not to disclose this to my family considering she doesn't want anyone to think negative for her from Day one. I thought it was an honest request so I fulfilled it. After our engagement on Jan 15, she told me that she goes for these yearly checkups to AIIMS. The reason given was that its a regular yearly checkup which happens due to the operation performed in childhood. I went with her on Jan 21 to AIIMS & it actually seemed a regular checkup as the visit to the doctor lasted only for about 30 seconds during which he only said everything is OK. Then we got married in April after which she again said the next visit is due in July, we went to AIIMS in July as well and this time she told me that she may have to take a medicine this time. When I asked what for, she said "just because there should be no complication in future since we just married". I still somehow bought this statement as she was absolutely healthy & active and no signs of any disease whatsoever.doctor this time told me that she cannot get pregnant for next 6 months due to this medicine, I had to be OK with this as well. Six months passed, we went to AIIMS again for the so called regular checkup visit & were told by the doctor that this last time she should have the medicine again & this will be probably the last time. I was OK again, stupid me ! Another six months & this time doctor suggested that she will have to take some pills now for 2 months since he did not want the thyroid problem to reoccur. Now I am getting frustrated about what was going on but still somehow thought its just 2 months so lets go ahead. We continued to visit the doctor every six months & he every time suggested the same pills & advised not to get pregnant. Now her health has started to be affected, back pain, joint pain, skin dryness, rashes etc. which on my research I found is due to that medicine. On May 25th, 2015 when we went to the doctor for the so called regular visit, he said Chemotherapy karni padegi & at that moment, I was shocked to death. He said she has Thyroid Cancer & has tumors of the same in her lungs from last 15 years. He specifically asked me - "Didn't she or her parents tell you that ?" Doctor literally scolded her like anything saying "maine kaha tha bina bataaye shaadi mat karna". She kept on listening quietly without even uttering a word. Doctor also clearly said that her father knew that its very difficult that she can have a child. Now for the first 2 weeks, she said she told me Thyroid issue thinking cancer is gone but after 2 weeks she suddenly said that maine sab kuch bataaya tha that I have Thyroid Cancer & you accepted me the way I am. When I asked her father why did not you tell me that she cannot have a child, he says he forgot! Bottom line, Girl & her father played with me big time & now not ready to separate legally since they very well know now they cannot get her married again. they want me to live with her till the time she is alive. By the way, Thyroid Cancer has a very long survival, as per doctor she still has about 10 to 15 years easily. My questions are:- Can I get this marriage annulled ? We got married on April 15, 2012. Can I get a divorce on medical grounds or on the grounds of this fraud and misrepresentation of the disease ? I am scared of girl using all her women powers in the court if I file the divorce, how do I cope with that ? Her father is a millionaire, can that influence things if he uses money ? Please answer honestly on this one. What do you suggest I should do ?