How do you tell someone your married to that you are not in love with her and want to end the relationship?

We have been married for 13 years but not together for the past 3 years( leaving in two different homes). The plan was to work on ourselves and then come back together. Where going through some hard times, I lost my job, just unemployment, fighting about the children, fighting over the house, the BILLS, not making the other person feel like they where number 1, I was smoking weed(which she wanted me to stop but she know I was smoking in high school )and it goes on. But the more I was away the more I grow apart from her. At first I was trying to come back home but I was not over some of my bad habits yet. So I could not come home. Mean while another woman has come in to my life whom I have fallen in love with. She excepted me for whom I am with all my down points. This other woman has lead to Christ. Stay with me through all my hard time ( I am banker in these times) she has uplifted me when I was down. I have informed my wife of her but NOW she wants to except me back with all my problems. I want to move on but my wife wants me back. The another woman is so GREAT to me but I miss my children. Plus I am having a hard time telling my wife I want to leave her. I am not sleeping and this is making me sick. How can I get through this.