This is no small matter. It is the very core of your problems. Well, maybe not the core. The core is all those FOO issues that cause you to have the low self esteem and to be so enmeshed with your wife. Your sense of self is the manifestation of those issues. This is where the rubber meets the road.
Schnarch will help explain some of this. I think you will also need to learn about your codependency, which Schnarch does not go into. He explains how your codependency interacts in your relationship and how you need to stop that interaction. Curing the codependency and looking into your FOO is outside the book. So you might start by looking into your past to review how your parents, or others, treated you, put you down, abused (verbally or otherwise) or abandoned you( literally or emotionally) and why you are so needy.
I am a little reluctant to start up this topic since after today I will be on vacation for two weeks and won’t be able to reply much (though I will try to read posts on my Palm). But this is very important for you, so I bring it up.