Need Divorce

I am a 38 year old man who has now been married for 6 years. I also have a 3 year old daughter. From the time of our marriage, we stayed with my parents at their house. Things were fine for the first two years ... after which she started fighting unnecessarily with my patents over petty issues. When things got out of hand, i had to shift to a rented place close by three years ago. I thought the change of house and our new born daughter would change everything. It only worsened. She constantly nags me and now i have become the sole recepient of her mental torture. Slowly i started working more and would come home very late from work as i did not want to face her. Over the last two years our i tried keeping the distance and we rarely talked, leave alone any physical relationship. In the last 2 years i have told her many times that i want to get out of the marriage ... but she says she wont give me a divorce. Now, since the last month i have fallen in live with a single woman at work ... but i know we have no future together as my wife wont give me a divorce and neither will she her mental torture give me any peace. Please advise how can i get a divorce