Cheonsa, this will be my first post on this board, and after reading your situation, couldn't help but respond.
I am in a similar situation, it has been just a matter of months since my spouse shared her (on online forums is the only place I currently get to honor her gender identity with the use of female pronouns which is my personal desire, so that is how I will refer to my love here, but you should never feel any shame in using whatever pronouns you and your spouse feel comfortable with right now between you) gender dysphoria with me (I was the first person she had ever talked to about this.) She did a marvelous job of communicating her experiences and feelings to me; she had written a lot about her thoughts, feelings, and experiences, and had me read it. A complete surprise for sure, but I feel like I have been in a very good place in my life and perspective to understand, and to not be too scared of the adjustments this could mean for us, which we both feel very fortunate for. But I can easily see how at other points in my life, or if things had gone a little differently, it would have been much harder for me to wrap my head around and understand and be able to deal with this.
I had never given much thought to my orientation before this, but happily have turned out to fit in the category of bisexual in this situation.
We have elementary aged children as well.
This is a journey with much uncertainty before you when you are first coming to terms with it and trying to figure out what that will mean for you and your family. The support of others that have gone before has been a true life line for us at this time. I have been making connections with people on the Pink Essence website/forums. Fiona Corwin is one contact from there who has been exceptionally kind and helpful in reaching out to us. She has successfully transitioned and she and her wife have stayed together in a happy relationship, as I am starting to find is not such an anomaly after all...there are couples who do go through transition together and remain happy together.

Fiona sent me these links to her blog and youtube channel, which she said she made just for the purpose of giving back and hoping to help others who are going through a similar journey. I plan to look at these links myself soon.
http://fionacorwin.tumblr.com/https://www.youtube.com/channel/UCNTLAl1aR8GpHCgRlwJc6rw/videosI have been reading a lot, and one of the books that I (am still reading and) have found very helpful in providing a framework of understanding that seems to fit and echo my spouse's experiences with dysphoria, is Julia Serano's "The Whipping Girl" (don't let the title scare you off). I highly suggest reading chapter 5, if nothing else (though I think the whole book is good, don't miss this chapter!) I'm in the middle of chapter 6, and that is also very good. I also am glad for reading Jennifer Finney Boylan's books "She's Not There" and "Stuck In The Middle With You: a memoir of parenting in three genders." I've also read "Transitions of The Heart" which is a bunch of essays written by mothers of transgender individuals, and the last essay in that was particularly touching when taken in regards to what support from those closest to us can mean, and the natural fear that can get in the way of us supporting, and the beauty of what it means as either a parent or a loved one, to face those fears and nurture the one we love by taking their hand and being there for them in the face of something that can be scary and overwhelming.
(It dovetails beautifully with the message in "Stuck In The Middle With You.")
We personally are currently trying to figure out how to plan for financial and job security that will be required to facilitate a successful transition (particularly because of how this will affect our kids if we are not financially somewhat stable), dealing with how to help my in-laws to better understand (they are the only other ones that my spouse has come out to so far, and while trying to let us know they still love my spouse, have simultaneously not been very understanding, have said rather hurtful things, and are placing a lot of pressure to conform.) We are hoping that if they can come to be supportive, my spouse will have a better time with siblings when they are told. It is so emotionally difficult to face rejection or disapproval about such a sensitive thing from those who mean the most to you.
We are lucky enough to live in a state where it is illegal for employers to discriminate based on gender identity and expression, but that does not necessarily mean that things will go over well at work. The ideal would be to find a job with a company that has good gender identity policies in place and insurance that covers transgender medical care. The Corporate Equality Index is something you can look up to find a list of such companies. However, we likely will try to make it work at my spouse's current job, but are trying to formulate back-up escape plans!
I am not quite sure about what all the legal issues once my spouse legally changes her recorded gender will be, but I know Boylan (the author of above mentioned books) seemed to indicate that their marriage still legally stands as long as they never divorce, even in states that don't recognize same sex marriages. I think I'll be researching and searching for more professional legal advice on those types of issues once they become more pressing for us personally. Right now I live in a state that recognizes same sex marriages, so that relieves some of the worry.
If you are interested, here is a link to a conversation on Pink Essence on the spouse support section, that I and several other spouses chimed in on.
http://pinkessence.com/forum/topics/tg-hitting-a-wall-with-her-gg?id=1451021%3ATopic%3A538251&page=4#commentsKeep reaching out. I know how isolating and intimidating facing this at first can be. You will find help, people in similar circumstances, and answers to your questions in time, as you keep casting your net out to find resources and make connections, even if it takes time.
My hugs and best wishes to you and your spouse and your little one.
-Felice