I lucked out in this regard, I always kind of knew I had some GD issues, but I made sure that I chose a wife based on my real core identity and personality, and not the male front that I had built up for the rest of the world.
And I had the good fortune that I listened to the advice here and on my other forum about partners. You really need to talk to them as soon as you can in the process if you care about the relationship. Waiting months into HRT is going to be worse than telling them earlier on. If you have started things already, sooner is still better than later. GD may be hell on us, and unfair for us, but the fact that most of us really don't know exactly what is going on until we are in a relationship is not fair to our partner either. Frankly it is society/cultures fault for not handling gender variance in an open and sane way, but it is critical to respect your partner's POV too. You have to do what you have to do, but honour them as well. Besides, how far down the path can you go and hide it from a spouse? Far better to disclose than get caught.
I lucked out that my wife already kind of understood GD and trans issues, and she recognizes that much of what she loves me for is who I really am, perhaps even because of my gender variant non-binary self.
We have kids too, I also worry about being a good parent, and dad. But even if once talking with your therapist (get one if you don't have one) full transition is your path, your family needs you, and getting a relationship through this takes hard work.
If she doesn't know what GD is maybe start with that, because that is a core issue, it is the demon that can kill those of us that have it. If she doesn't know about the GD she won't understand the very real agony and terror that can come with it, she won't get what it means to look in the mirror and not see yourself, for years. Trans is more a cure than a condition the way I look at it. I like what the others said about not over-sharing in the first conversation, because you need to let her know, but the first conversation is more about her needs and fears than yours in a way. Emphasise that you love her, and always have and always will, that that won't change. Maybe find her a good non-toxic partner support group, site or forum.
- Jaded Jade