I'm sorry, Robin. From the sounds of it, your wife has committed her mind to seeing only negative outcomes. They are possible, of course, but so are infinitely many others. It's very (very) difficult to negotiate let alone collaborate with someone who only sees negativity.
I know we've batted this idea around before, but I'll bring it up again just to see if anything has changed. Do you see any way to approach this in small increments? Changes in clothing, hair, anything small, get her used to it and maybe seeing that it isn't the end of the world. If she can adjust to that, then maybe the next small step? I know, it still sounds nearly impossible, but I wonder if she can be acclimated gradually.
The reality is that the husband she's afraid of losing doesn't exist in the way she imagines. She's clinging to a fantasy and doesn't realize it. She's not happy, you're not happy, so what is it that is being preserved by maintaining the status quo? Two people's unhappiness?
It also sounds to me, though, like you are clear and committed to proceeding with your transition (somehow). I applaud you for that. You need to know what it is that you need to be at peace in your life. If you're communicating that clearly to your wife, and she still wants you not to, well... I think you both know where that leads unless one of you changes positions.
I wish you the very best. I think you're doing an amazing job of managing this stress and still taking care of your soul.