I haven't read your full sitch, but can relate to what you're going through. Everything you do now is for your kids and you. Not her, not to send a message (except that you will be ok w/out her).
You say you've lost yourself and have defined yourself completely through your family and work. Who did you used to be before you were married and had kids? What did you like to do with your free time? What have you always wanted to try but haven't? I know it seems impossible to think of these things now, let alone motivate to get out there and do things when you'd rather lie around and do nothing, but it will help--
When the men on the chessboard Get up and tell you where to go; And you've just had some kind of mushroom And your mind is moving slow; Go ask Alice... I think she'll know.
