Someday you will find the courage to talk to your wife, you'll know when it's right. And hopefully you'll get the understanding you need, most of us seem to. If you married because you love each other and you still do you probably will.
You're right about "underachieving" and feeling "inferior"- it doesn't matter how clever we might be, abuse leaves us feeling that way, but it is possible to overcome those feelings.
But it's hard work, make no mistake about that, and I would strongly reccomend a good therapist. Find one that knows about, or solely deals with, SA.
It's tempting to think that because we think we're "smart" we can do it ourselves, but personally I don't think we can. We need guidance, someone to make us think of all the angles, without that we go round in circles.
But you've made a great start coming here, telling us has relieved you of part of the secret, the most important step.
There's a good feeling here, plenty of support and help, and somewhere to unload.