I can't really address all of your questions...because I'm not living the same experience that you are (married, three kids etc.).
But...for me it was transition or live the rest of my life as a miserable feminine guy with the body of a gorilla (my genetics predispose me to extreme excess body hair and baldness). Being male (Im in the process of transitioning) also affects my social life a lot...since guys seem to think that I share every single interest they do (sex, alcohol, girls, etc.). So in general...gender dysphoria is part of my main reason...the other part is that I identify more with females (mentally, sexually, emotionally, etc.).
Coming out to my parents was difficult as they are both strongly Christian...and it changed their relationship with me quite a bit, not necessarily in a 100% bad way...but they don't like that I'm transitioning. Overall everything is pretty good so far...
From what I can tell...your wife wouldn't handle it too well...so be prepared for the consequences of telling her (arguments and possibly divorce...although it COULD turn out the opposite).
Also, you should be pretty strong in your gender identity...since you will be questioned and possibly discriminated against by others. It also helps to be sure about your gender identity if you want to get irreversible treatments such as hrt and or srs (or other misc modifications). In that right you may want to see a therapist that has knowledge/experience with transgender people, that would be your first step in transitioning or even just gender questioning (if you are).
Warm wishes on your journey,
-Skye