I echo that it’d be best to level with your missus, and at soonest. Diffuse the situation that you strongly suspect has already dropped cones of silence –verbal and emotional– into your lives.
YouTube.com and TED.com have great materials that could be useful for you both, and are way better than printed matter. As a couple, viewing and hearing real people discuss their trans realnesses and related matters/issues is incredibly educating. While watching, the both of you have opportunity to dialog.
Preparation can only help. It may be useful to, beforehand, setup an account on TED.com and familiarize yourself with how the website works. On both and beforehand, do look-ups on the the subject ‘transgender.’
A second piece of preparation is to (begin to) layout your plan for going forward, if you want to ‘go forward.’ Maybe you want to keep your trans-ness between just the two of you? Maybe you want more? Your end goal(s) needn’t be defined right yet. Hey, it is hard do imagine paradise while in the foxhole’s mud, no?
My missus wasn’t happy when I told her. She didn’t pop her top, but she was confused and needed processing time and processing help. You are the best one to help her process it; nobody else whomsoever.
Me, I feel I am a ‘blended,’ both female and male simultaneously. A combo. I don’t feel to be a woman, and I know since forever I am not a ‘man man.’ Rather, I feel ‘n think of my me as a ‘twoman.’
I’m 73 y.o. (almost), out since ’05. I don’t regret at all that I didn’t coming earlier: it could have occurred only when it did. Neither do I have second thoughts about how I outed myself: it could not have happened differently. (I don’t Monday Morning Quarterback, ever. ‘Waste of time.)
And, I’m no-op to this point. Gender is in the mind and attitude. Natal sex is not gender. Even with surgey I would forever be a gloriously blended twoman.