I'm both bi-gender and spouse, and I've been through this twice. First when my husband first came out to me 18 years ago, and again in December when he announced he needed to take a first step to transitioning.
The first two weeks were ROUGH the first time. You think your emotions are rough right now? You just dropped her world out from under her. Yours are not the only difficult thoughts and feelings right now. Your wife will need time and probably counseling, and a lot of education to understand the scientific cause, your feelings, and to be able to sort out her own feelings, her fears and her idea of her future either way. In my case counseling and lots of talk revealed that I was so upset about it because I also have gender issues, which were part of the reason I reacted so badly.
The second reveal was much the same. Even though his being transgender was not news to me, for about two days I was numb and in shock. On the third day my brain started functioning again and I began working through it all. Still, the idea of being married to a woman was the end of my world. As a bi-gender person I need a *man* in my life as a foil/support for my feminine side, to make her feel feminine while my masculine side's pressures often makes me feel dysphoric, neither here nor there. As long as I can perceive my husband as masculine/male, I'm okay.
So, we worked together, and with a therapist, to come up with a solution to keep our 29 years as a romantic couple intact, which includes a lot of things not common to trans individuals, such as not switching gender pronouns or names. We both know there may come a day when either my own dysphoria or his become too much and one or the other of us goes too far to allow our relationship to keep working, but we're battling as hard as we can to save our marriage. It's worth it.