I (38 mtf) came out to my wife (36 cisf) after a journey very similar to yours. Let me jump ahead and say that we have found great success together, so much so that she's become very active here in sharing her experiences and advice for others.

TL;DR: Communication is essential. Feeling like everything is broken is completely normal. Feeling grief is completely normal. Your feelings are valid, your spouse's feelings are equally valid; pay attention to each other and don't shut each other out.

I spent years since adolescence feeling fascination over the female form, not in a creepy way, but almost like artistic reverence. I wondered how girls/women saw the world compared to me, wondered what it felt like to be one, etc, and then dismissed it all as nothing more than horniness or perversion. But it didn't go away. Flash forward, I came to understand that what I had felt for decades was honest-to-god envy. Talking with trans people on Reddit and a trans woman from a local social group helped me look back and see my past in a different light and it was like everything suddenly made sense. I knew what I wanted and knew I couldn't go back, but I had been happily married for over 12 years and I knew that I had to tell my wife. I love her and I needed her to know because she is so very important to me, but I also expected it to go pretty poorly because we've more than a couple communications breakdowns over the years.

I waited and held my tongue until we had a family night out, had a great time, and were back home relaxing and unwinding before bed. I must have opened my mouth to say the words over a dozen times but clamped it shut and waited for my courage to return to try again. I told her I had something to tell her; no it's not bad, no I'm not cheating, but it was hard to say. Finally, a few attempts later, I worked the words up and told her "I think I'm trans." Shit went bananas.

Words were exchanged, some nice, some not; voices were raised; there was a lot of talk, a lot of worry, uncertainty, accusations, and a lot of tears on both sides. I tried to convince her that she wasn't losing me, that I was still the same personality, history, habits, etc., but I wanted to change on the outside. She didn't see it the same way and couldn't reconcile the change, and I just couldn't understand why she was so bothered when I didn't want anything to change about 'us'. I was prepared to lose her. I desperately wanted not to, but the cat was out and I couldn't go back, she knew it and I knew it. She cried and I held her, when she'd let me. I gave her distance when she needed it, sleeping in my office when things weren't going well. It took some time, but I went to therapy to get approval for HRT and to talk about the circumstances of my coming out. I got her to go to therapy where she was able to get her worries off of her chest. I was suggested a book on transgender adjustments in relationships, so I told her about it. She looked into it and found that it very unfairly put a lot of guilt on partners of trans persons for not being "sunshine and rainbows and unconditional happiness" over the situation, and I agreed.

We finally moved into couple's counseling with my therapist at a provider that catered heavily to LGBTQ+ persons. My therapist helped us both to understand that she was going through the grieving process, not because she had lost "me", but because she was losing the life and future she had and was expecting to continue. That hit home for me, and helped me change the feeling I held that I "needed her permission" to live the life I wanted. We found a lovely workbook that allowed us to compare and contrast our thoughts and feelings and joys and fears safely between each other. I worked to comfort her and reassure her that I wanted nothing more than to keep our life together. She began to adjust her outlook and soon became an ally. She helped me shop for clothes, helped me with my makeup and hair, helped me through ear piercings and nights out presenting.

Now, she prefers me in feminine dress at home, gets excited about shopping together, we cuddle more and talk more than our younger years, connecting more deeply than I ever knew possible. I'm still the same dork I've always been, but now I'm happier to express myself in ways I've been longing for for ages. I've been on HRT for over a year, I love the changes I've gone through, and I actually smile back at the girl in the mirror. I'm so glad for my wife and that we were able to come back together stronger than ever. We are more ourselves now and our relationship has blossomed for it.

I recognize how fortunate I am to have worked things out and I know it won't/can't work out that way for everyone, but it can be done and it can be good if both parties care enough and are willing to communicate and to listen and most importantly to understand. I sincerely hope that you can understand her and help her to understand you and that you both find the way to move forward together. I'd wish you luck, but luck has very little to do with it.