Jayne, I get it and you said this would happen -- returning to a painful place.
It's not easy, in my view no life worth living is always easy.
I think most of us experience what you're relating now and as someone who will certainly never pass the way I'd like to -- I'm never going to be a size 4 girl - I'm conflicted nearly every day.
I'm a pretty ok looking male and I know I feel significant envy for those who pass easily **and are cute, attractive etc**. I also know that those girls have just as hard a time as I do.
Given that my chosen profession is blowing glass and metal sculpture and I really like to do large work, my size (5' 11" 220 lbs) is also a blessing and I have no interest in losing the muscle mass that makes that possible.
So I'm working to look more femme, hormones have helped me feel better about myself and also sapped my sex drive (I will be talking to my endocrinologist about this and the possibility that adding progesterone could help)
My gf of 18 years has always known me as trans and I didn't even tell her when I started HRT because I needed to experience myself on estrogen without an unhappy conversation about her not being lesbian. When I did bring it up the conversation was even worse than I'd expected however at least for now we still love each other and the impact on sexuality is something we're both handling OK.
So from my POV you're lucky to have a wife who's not immediately panicking. (My GF's immediate response more than a decade ago was "I'm not a lesbian, how does this impact me?" and as I said her response to my decision to start HRT was initially even worse.
I know this doesn't translate to 'easy' still, I'm confident you and she will figure it out. Transition doesn't require any specific outcome, yet the one thing I think won't work will be denying it.
Best wishes
sb
