PhillyB

First off, never put anything in writing you wouldn't want your worst enemy to read.

Sounds like your wife may be guilt ridden at the moment since she is willing to walk away without any financial compensation.  You may want to move quickly to make that legally binding (if possible) before she changes her mind.  Financial holdings may not seem so important at the moment, but they may provide options in the future that otherwise wouldn't be available to you.  

Ultimately, you can only control what you do.  Your wife has decided to move on with her life, you should do the same.  Try to focus on tying up any remaining loose ends between the two of you with as little drama as possible.  Emotionally that is a lot to ask, but the last thing you need right now is for your wife to get it in her head that she is the injured party in the relationship.  That will only make it harder to come to a mutually agreeable resolution.  

Also, please keep in mind that your wife will always be the mother of your child.   So, for your child's well being it is much better if you two part ways with minimal drama and hate.