I saw the "IM" signal and came as soon as I could, what seems to be the problem commissioner?
Well first and foremost I think you are confused by your wife's actions and words because she is confused by them too. Speaking from experience she needs reassurance (as it has been mentioned) because I imagine she is feeling less than adequate to put it mildly. No matter how you have explained it or rationalized your mindset to her inevitably she is feeling unwanted and feels like now she is in direct competition for a prize (you) she thought she had already won. Best thing you can do is reassure her that you love her and that while this change is something you need, the "new you" is still in love with her.
Any insecurities she had about herself, your relationship, or her life in general just had a magnifying glass put on them by telling her; by no means should you have not told her, but be prepared for peaks and valleys of being ok or not ok with poly. I think her actions with the time spent together (your self described NRE with your wife) are her attempt to show you she can be what she thinks you want her to be, she may be trying to show you she can be what you are looking for. I say this because at first I saw poly as just a way for TP to sleep with other people (it wasn't but that's how my emotional side viewed it) and I imagine your wife might have the same feelings and is trig to compensate for shortcomings she thinks you believe she has. Reassurance is key, and honesty about what you really want (physical vs. Emotional for poly.)
I should point out that when TP and I first started dating she made it clear that she wanted nonmongamy but was willing to work up the trust before opening the relationship; your wife didn't have that benefit. Hard question time: do you want to stay married and be nonmonagmous? Or are you convincing yourself you still want to be married for your son and because it's the status quo? So it comes down to you really wanting nonmongamy or saying you want it to rationalize feelings for other people and a wandering eye? (neither are bad but there's a distinction to be made between those and Poly.)
I had to ask similar questions of TP when it came time to open the relationship: did she still want to be with me or just be back single and dating again?
Ultimately your honest is your biggest credit right now but dont take her mixed messages at face value; as was said she needs to know you value her feelings in this.
Polyamory is wrong! It's Multiamory or Polyphilia. Mixing Greek and Latin roots? That's wrong.