I'm at like... the exact same place Gypsie, except I'm about to become single and I never told my current girlfriend. (It's not big deal, she's moving away and we can't keep the relationship up.)
I was actually going to make a similar rant today. So... you're not alone in this.
Concerning what to do about it? I've been doing little courage building exercises. Thinking about telling people... buying stuff from stores in my city but ones I don't normally show my face in.
Then I stress out, and get high instead of dealing with these awful thoughts in my head.
Most recently:
I realized that my need to be female normally starts as a want. Sort of an itch. "Gee, I'd like to be wearing my girl clothes" or "That lipstick in my drawer is sort of calling." And when I scratch the itch, it just comes back stronger. I've been thinking like "maybe if I don't scratch the itch, it will go away." Possibly carrying a metaphor too far, but, it's a thought...
Cuz like... I've been feeling lately like, y'know, I didn't ask for this. And I've got my life, my friends, my family, my academic career, my financial life ain't great, and stuff. And like, I don't wanna lose my friends, my family (for financial more than sentimental reasons, I must admit,) and I definitely don't want my love life to go to hell, but that's like... a for sure thing when I don't already have that "sure thing." Then I realize, "This makes me happy, and it motivates my lazy ass..." so it's good for me in a way. And I can't really sort these thoughts.
And like you, I've been experiencing internal changes and embracing my female side at least internally. But yeah.... I feel you.