hi Lucy...
I can only give you my perspctive as an SO of a TG, and also that as an SO of an OCPD and OCD male (my ex husband).
Deception is the worst. It makes us feel "less than". There is going to be an emotional hurdle for your wife and even some of it will prolly be ego driven. She is going to ask herself what SHE did wrong, what she could have did different, and what is going to happen to her and change in her life.
When talking to her, I think you need to approach her with the answers ready ahead of time, and approach her on HER level. Although this situation IS all about you, in telling her you need to make it all about HER and how much you love her and that you are telling her and trusting HER because of that love. And that you do not want the marriage to change. That your feeling about her are unchanged.
These things don't always turn out well. Be prepared for many reactions. Reactions that could even change day to day I think for a while. Trust that truth is paramount for both of you, even if the truth pushes you apart. Hopefully the truth will bring you closer together. Stay strong.
Good luck. If you need to talk let me know. If she would like to talk to another SO, let me know. :hugs: