Coming out to a spouse is never easy. Even in my case of a wife who knew since day one some 30+ years ago I had gender issues.
My wife and I tend not to be the dropping some news out of the blue types, unless the situation totally warrants it. If there is something important the other needs to talk about we essentially set up a meeting, or try to. Weeknights tend to bad for us both between my schedule and her health so it is generally the weekends. On occasion, the Moon may in the right position and the response will be let's do it now.
Having been a bad stutterer in the past, to be able to speak at all I needed, still do at times, to rehearse what I am going to say in my head so I can get the words out. For dropping the T-Bomb I sort of had a sheet of notes in a sort of outline form to stay on track. Within about 2 minutes that whole effort got blown away with the barrage of questions and her observations and commentaries.
Be prepared for the raw unfiltered emotional response. You may be thinking this is not such a big surprise for her, but.... You are totally turning her world view on it's head and she can be looking at living out on the street with 3 kids as a best case scenario. She has been lied to, betrayed, and now also plenty of self doubt for "not seeing this coming". For the most part she is correct.
Also keep in mind as the seconds, minutes, hours, even days and months tick by that this will be case. You spent a lifetime barely getting a handle on just feeling trans and very little time being trans, earmarked by deciding to take some steps about it. Your spouse just had this dropped in her lap with zero preparation. It takes time for something like this to begin to sink in. There will be the typical grieving process largely following the Kubler-Ross stages. Often times reinitiated with each major step step you take. (Major to her)
Communication is vital for the survival of the relationship. Love is not enough. I credit the extremely difficult honest and open discussions between my wife and I as the key factor in keeping us together for these past six years. A skill I had to learn fast.
For many trans people coming out to the someone like a spouse and not being struck down by a bolt of lightning, having the Earth open beneath you and swallow you up, or being hit by a meteor is a sign, or the inspiration, to go full speed ahead. The only hitch is you are not the only one on that ship. If you want to keep the relationship somewhat in tack, time is your ally. Of course, if you are barely hanging on to life as it is, time isn't exactly your best friend.
When she asks "What's next?" she is likely thinking you may be wearing a dress by the end of the week. "I don't know" is just as valid as any other answer. After 6 years on this journey I still don't really know what my plans are. I take steps, make changes, find happiness. I readjust as required. If you feel that you need to make some drastic changes in order to live another day, best get that out there. If you feel just making some little change MAY help, say it. For instance in the early days I needed my monthly escape from maleness which I got by spending a good part of the day presenting as female. At first my wife spent the day out shopping, eventually she asked if it was OK for her to stay home (BTW-I never asked her to not be home, it was her initiative). I almost always wore panties so no change there. That worked for me for many years.
Marriage is a partnership. Since no two people always think and feel the same about everything compromise is par for the course. Her needs to her are just as important and valid as your needs are to you. Communication is key here. It sounds like it won't be a problem but.... someone just may hold back so as to not hurt the other.
