The best advice I can give you is to talk to a counsellor about your feelings. About how you feel worthless without her. No one on Earth should "complete" us and no relationship can stand the test of time if we are not "whole" on our own.
You need to work on yourself. In all aspects that you feel are lacking. You do this for YOU (not just for your daughter or your wife). YOU deserve to be the best you can possibly be. And unless you do this - you will not attract the right people into your life whether you save your marriage or not. If you DO NOT try to improve your self and your self image - the good things in life will not be yours.
I wish you the best but you MUST make the changes NOW!
