Hi. My husband (he is still going by he) came out to me as MtF 18 years ago, went back in the closet, and in December he came out to me as being ready for the first steps of whatever his transition is going to be. It was rough at first, both when he came out to me and his new announcement, but over the past months we've learned a lot about how to navigate our new relationship. In the midst of the whole thing we figured out I'm also trans; bi-gender M/F. Which takes nothing away from the issues of our marriage and my mostly cis type reaction to his news. I'm still wrapping my head around my gender issues - which play into some complications for our own relationship, but I won't include those here. Only the point of view and experiences I see over and over among SOs, many of which match my own experiences and feelings to a T.
I have been fortunate enough that my husband has the better habits as far as what we need to do to keep our marriage together, and is also incredibly supportive of my own gender issues.
I am a member of some very private groups for wives of MtF transgender individuals, and between our own experiences and the many, many women whom I have talked to in these "safe places" I have learned a lot about how trans marriages work, and what blows them up. I hear the happy stories of those whose marriage is better today than before transition, and the stories of destroyed relationships, torn apart families, and the ugliest stories of all - suicide of the cis partner.
One of the shocking things I've learned is the high rate of suicide among wives of transwomen. Yes, because of their partners' transitions! In one group our moderator recently died by her own hand when she couldn't handle it anymore. In the wake of her death, four other members admitted they had attempted suicide in the past also because of their spouse's transition. So when you insist that you have to do this for your mental health, remember, you're blowing up her life and she has mental health to maintain too. Don't assume you're the only one in severe and serious mental pain! For many wives, especially in long marriages, their entire life and identity is wrapped up in their marriage. If they have no clue there's a problem in their marriage before the big annoucement it is quite literally the end of their world, especially if they're not mentally equipped to handle marriage to a transwoman.
If your wife happens to be bisexual and/or pansexual and is open minded about sex and relationships, you probably have it made. For some women it doesn't matter. You are you. If you're one of these lucky individuals, then you have a much better chance of making it work than the average.
If your wife is straight and traditional, even if she's somewhat open-minded, this may take a LOT of work from both of you to really keep a good marriage.
*Talk to your wife as early as possible. Putting off the inevitable isn't going to help anything. It only makes the blowup bigger than it may need to be. Also be aware of the timing of when you come out to her. If she's going thorough pregnancy and her own hormone issues, bad idea. Or freshly given birth/breastfeeding. More hormones. Don't do it around a holiday (particularly Valentine's Day, her birthday or your anniversary!), or a special day for her. If her grandma is dying, just, no. Use common sense.
*Don't expect her to take it well. Expect a few days to a week or longer while the news settles in and the shock wears off. Don't assume her first week's reaction is her permanent reaction. I was on divorce websites within hours, convinced my marriage and my life were over. I cried a lot. And I had 18 years warning! I knew he was trans, I knew it never goes away. Yet it was still like he had set off dynamite in my life. She may cry, for days. She may scream and rail at the world. She may simply go into shutdown mode. She WILL need time to get past the initial shock. And it may change from one thing to another before it's over.
*Get both of you into therapy immediately. Like, if you can pre-schedule it for a week after you come out, do it. Take her to your own gender therapist for her own personal counseling sessions and and couples counseling together. Having two messages - one from your therapist and one from hers - sometimes has you working at cross purposes. If your gender therapist doesn't take couples or the cis spouse, make absolutely certain the therapist she goes to is a therapist who is at least strongly familiar with gender issues and is in at least some contact with your gender therapist, so they can make sure you're on the same page. Regular therapists usually don't understand much about the trans world and challenges, and sometimes end up giving poor advice, working counter to what you both need in order to come together.
*Offer to take her with you to your medical appointments. Don't force her, but do encourage her. Not just to drive, but to ask her own questions, make suggestions, and hear it all for herself. To hold your hand. For you to hold her hand. If you plan to make your marriage work, include her in the process as much as possible. You are not going through this alone. You are going through this as a COUPLE.
*If you can safely (mentally) do it, slow your transition down so she can come to terms with each step. Don't stop it for her, but give her adjustment time. Ask she if she's ready for X. Talk her through it, both your emotional and mental need for it, and the actual medical stuff when applicable. As I said before, take her with you to talk to the doctor so she completely understands. Have your therapist explain if necessary. Are there any other options for your treatment that would take care of the problem? Consider them. I'm not saying she has veto power, but keep her in the loop for medical decisions. She's not only your partner in life, she's the one who will be physically caring for you while you recover from surgery and can't walk for several days. She's the one who will be dealing with a 13-year-old hormonal girl in a grown male body. It's not a walk in the park.
*Don't forget she's still a woman with a woman's needs. You may be feeling the need to be treated like a woman, but, SO DOES SHE. Don't ask her to take the role that was yours. She is not going to be comfortable with suddenly becoming the man in the relationship. Remember, she's probably a cis female. She's not going to transition to male just because you're transitioning to female! She needs flowers sometimes, and to be the submissive in bed, or the dominant, whatever you were before. She's still a lady. You may have to rework YOUR position and role in the relationship in the household, but DO NOT TRY TO TAKE HERS. Otherwise I guarantee it's going to go badly.
*Talk to her! She's not psychic. Don't expect her to know what you're thinking. Don't expect her to know what causes you pain, either mental or physical. Don't expect her to know what you prefer in sex, or what you really want to never do in bed again. Tell her. And be open to what she needs too. Ask her point blank. Don't beat around the bush or hint. Just plain ask what she's needing from you. And be ready to provide as much of it as you can. There will be times when you're strong and she's weak. And there will be times when she's strong and you're weak.
*Don't mistake honesty for an attack on you. If she can't speak her mind honestly about how she is feeling about your transitioning without you turning on her, then she's going to shut down and it's over. Will it trigger dysphoria for you? Maybe. Even likely. But listen to her. Her feelings and pain are just as real as yours. Your pain does not invalidate hers.
*If you have children, don't get so wrapped up in your transition that you forget you're also a parent. Being transgender isn't a free pass to get out of parenting and doing half the work of raising the kids.
*Don't abandon her for a newly discovered trans social life. If you have kids, get a babysitter and bring your wife with you to dinners and gatherings. If she was a part of your whole life before, she should be a part of your whole life after. Don't start going off on "trips" with another transwoman for bonding and friendship. Your wife should still be your best friend. Sure, it's okay to have trans friends with whom you can share your experiences and such, but if you didn't go off and do stuff with your friends before, doing it now will only send your wife the message that she isn't enough for you. She is inadequate. And it hurts.
*Go shopping with her! You may both find awesome outfits, cool new makeup colors and she may have some great tips on women's clothing. Make it a bonding experience together.
*Take her to a trans conference or local/regional gatherings. They almost always have sessions for spouses, where spouses can meet with others who have been through what they're going through now. Being able to talk to someone directly, face to face, to cry on each others' shoulders, is worth more than all the internet groups in the world. Also, being exposed to other trans individuals who are farther in the transition process than you are will help her get an idea of what her future may be like.
Thank you for considering my advice. It may not be right for every situation, but please, keep this in mind.