I believe that what is happening is that your wife sees you doing things and in her mind, she thinks that you are only doing things to get her attention. She knows exactly what buttons to push w/you. Also, if you are out there doing your thing and she goes darker than dark on you or her attitude flares up. Right away you begin to think that whatever you doing isn't working....not true. If she didn't see what you were doing, she wouldn't be reacting the way she is.
My advice....stop and think about what you are doing. Are you doing and/or making changes to get her attention/reaction or are you really doing them for you? If you are doing them to win her back, then stop right there! This will not work. The changes have to be for YOU! The changes must become a permanent part of your life and you cannot revert back to them if you think they are not working.
If she is set on moving out, let her go. She needs to see and experience the cold cruel world for a while. She needs space and time to think about her life and where she wants to go. You cannot change her mind right now, so drop the rope, concentrate on what you can do for yourself and your children.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.