Like everyone else has said, nothing you've written or feel makes you a bad person. It's *very* early yet; you should expect to be in emotional turmoil for a while, and your spouse has no right to expect you to be fine with everything overnight. Some women can only see themselves partnered with men - and that's 100% valid, just like any other orientation. If people wouldn't expect you to "stop being gay" by choice, they also shouldn't expect you to stop being straight. My one caution there is to listen to the people here who've said that the label isn't the point, and that if (and it's a BIG if and I'm not saying you should or will get there) you find yourself at the point where the only thing holding you back from remaining with this person is "having to become a lesbian" you may want to consider saying to heck with the label part of things. I do know more than one self-defined straight woman who is with a trans woman, and more than one lesbian who is with a trans man, and some of them even insisted on keeping their "original" labels and just made an exception for a beloved. However, again, that's not the point right now; you are utterly entitled to prefer men exclusively, and if that's still the case, as the transition progresses you're going to be less and less romantically interested in your partner. Which is painful and awful and I sympathize so very much.
My wife came out to me just after our 9th wedding anniversary. She hadn't been lying to me - she only figured it out herself a few days before - but like you, it was a total shock and my entire world tipped sideways. I will say up front that by a year later, she had fully transitioned and we were still romantically involved and still very happy together... but at 2 months in, I was depressed, angry, worried beyond belief, suicidal, frustrated, and generally miserable. I couldn't go 12 hours without crying hysterically. I was a lot more upset than you sound, though possibly not as much as you feel. And I am bisexual, which meant that I and everyone else thought it'd be "easy" to adjust my sexuality and my life to this transition. It wasn't. I'm being brutally honest here : it was incredibly hard, and there were times when we had to find ways to adapt to the new state of our relationship and compromise with each other all over again, even though she was and is still fundamentally the same person. Furthermore, had she gone ahead with doctors and treatments without waiting for me to catch up to the new state of affairs, I would have been 1000X worse off at that point. (She waited until I was ready, which was about 3 months after the revelation, just to see a therapist.) Each time something changed, I had to grieve for what I'd lost before I could appreciate what we'd gained. It is a tremendous amount of work for both the trans person and their partner to weather transition together, and while it absolutely can be done, there is no shame whatsoever in deciding that you simply cannot be married to a woman.
I think my only advice at this stage would be, as others have said, to seek out a therapist for yourself and/or with her, and see how you feel about the next few weeks or months. (In fact, therapy is probably a good idea just to deal with the trauma of this revelation, regardless of where things go from here.) Don't worry about years from now yet, if you possibly can. So long as the answer to "Do I want a divorce" is "not right now," keep working through things with the therapist and your spouse. Of course, if that answer is ever "yes," or she's unwilling to meet you partway on this effort, then you'll know the time has come to end your marriage... and don't let anyone reproach you for that either. You'll know you tried your best. Good luck.
(Jess42 : I tell people that we've changed a heck of a lot more since age 17 [when we got involved] than my wife did in that transition year, although she certainly changed a lot faster that time. I barely recognize the person I was back then! I often mention the same thing about physical changes as well.
I'm not sure anyone who hadn't seen me in 10 years would recognize me either, and yet she loves me still. The love and connection is real, definitely, even if it's not always enough to survive this drastic and unexpected a change. It's not shallow to care about the physical packaging, even to the point of dealbreaker, but it's also ridiculous to claim that a transitioning spouse becomes a stranger overnight.)
