How difficult this must be for you. I think you are absolutely right, the first thing is for you to be comfortable with your feelings.
I never really had any issues about wanting to present as a woman. It began for me when I was 13, and to be honest I think I assumed I would “grow out of it.” But throughout my life, since then, it felt right.
I was married 20 years before I was able to tell my wife. It was not something I planned, a situation arose and it just happened. It took a few weeks of giving her more and more details before I came out totally, and it became clear to her, this had been going on since my early teens.
Lots of talking about it, but she became more and more relaxed about it, and soon accepted me completely. There are compromises of course and I have always cared about her feelings, but it was so liberating and led to me being able to live much of my life, at home, as a woman. I am still in the closet as regards family and friends.
The major difference is that you may feel the need to go much further, transition and possibly moving towards complete gender change. That will be much more difficult for your wife to handle I am sure. But it will be a major step forward for you if you can take that first step with her.
I wish you well and hope you have all the support you will need