Dual Relationship

Dear Sir, I am a married person having three daughters all under 10 yrs, since four years I am having a extra marital relationship with a lady (Unmarried-age 32) who was my crush at college. That lady is educated and working and earns good income. Though I don't have any interest in we income. My wife and my mentality doesn't matches she is egoistic and rigid in some mater but in terms of caring and respect she gives respect to my parents and me. But her thoughts are narrow and I cannot able to adjust with her since long. When I talks for divorce with her she totally refuses and says until I am alive will not give (typical Indian lady). Also gives threat of police complain against me and my extra affair lady. I do. Want to take care of my wife and my children but I want to spend life with that lady and want to marry her. Please advise in such case what is the legally right move we have to follow so that I can get divorce and marry my lady and also can take care of my children and to be ex wife. I have discussed all issues with my present lady and she has accepted all my circumstances ready to help in fulfilling all my duties towards kids. Thank you,