Is it lawful to agree with the wife to give up her rights?

Q: I have two wives. I have been married to the first one for twenty years, and we have four sons and five daughters. I have been married to the second one for three years, and we have one daughter. The last three years have all been miserable, mostly for my first wife. I have tried so hard to treat both my wives fairly and equally, but I am still failing to do it. Because of the problems, I began to hate my first wife, to the extent that I used to force myself to have sexual relations with her. I am still married to her for the sake of our life together and our children. However, I cannot bear what I am going through. In 22/2/1405 A.H., her brother came and we were all sitting together. After an argument, I told her I could not bear to live with her anymore. I did not have the intention of Talaq (divorce initiated by a husband). Then I told her brother to discuss with her what she wanted. I meant that she could either have Talaq or stay (Part No. 19; Page No. 192) and live with her children, on the condition that I will not live with her but I will provide for her housing and food from the Nafaqah (obligatory financial support) I send to my children. However, I cannot bear to live with her, and I decided that this was my last night with her. She replied at once that she would not leave her children. I told her that she did not have to leave, but I was not going to stay with her anymore. Now I am thinking, for the sake of the old days, and out of mercy for our children, to let her stay with the children in their separate house, provide her daily sustenance and clothing twice a year, treat her if she becomes ill, and drive her to her family at least twice a month, in addition to any emergencies. All this is in times of ease; whereas in times of hardship, we will share whatever we have, even if it is one loaf of bread. Since that day, I left her. However, we live in the same house, each of us in a different apartment. My questions are the following:Firstly, does this contradict Shari`ah (Islamic law) and am I a sinner?Secondly, have I done well, or will I be considered a wrong-doer or wronged for the rest of my life?Thirdly, is it better for her to stay with her children - if she chooses to - or to have Talaq?Fourthly, am I obligated to divide sustenance between my two wives equally, (Part No. 19; Page No. 193) given that my second wife is the one who will care for me?