Welcome to a place that no one really wants to be. Having said that, I'm so very glad that you found us for support.
You know, it matters not in the least, as to the orientation of your spouse, his physical sexual characteristics, or the state of transitioning. Not one bit. Nor your orientation, etc.
What matters is, that you took vows to each other, sacred vows, that you would forsake all others and cleave only to each other. And he has shattered those vows. He has betrayed you. That is the important fact to carry forward. And "it's only sex?" Oh pleeze! That's the un-original battle-cry of EVERY wayward spouse.
What has essentially happed to you, is that your WH has driven a bus over you and left you bleeding on the side of the road. Right now, as much as it hurts, you're still in shock. Unfortunately, I have to assure you that it's going to hurt much worse, when the shock starts to wear off. I won't lie to you this is a long road that you're going to travel.
Please start off by looking in the upper left corner, in the yellow box, and clicking on The Healing Library. Start reading. Knowledge is power and you will need the knowledge that is in there. Take a look at the first 3 pages of this forum and read any post that has a red "target" next to it. Also good knowledge for you to have.
I assume that your WH has a councilor. This is definitely a time for him to continue receiving IC (individual counseling) to get to the bottom of his broken value system that says that it's OK to screw another person other than your wife, but ONLY if the IC if marriage friendly. I say this as a person with several friends who are in the process of transitioning and who have completed the physical process. I don't care what new exterior you have, if you're married, you are committed to a faithful relationship with another person. Your WH has shattered his vows to you, and that doesn't make him an explorer. It makes him a liar, a cheat, and an adulterer.
You need to take care of yourself and put yourself first. If you don't take care of yourself, you will not be able to take care of your child. It's the airplane oxygen mask drill put it over yourself and then over your dependents. Rest when you can, eat what you can, if you can't eat, get whole food nutrition drinks (Ensure is one) and sip them. Stay hydrated but stay away from booze. And keep coming back here for support. We've all got your back.
I believe that you need to have x-amount of posts before you can use the PM (private message) function. Once you get there, if you want, PM me. I have a lot of experience/friends in the LGBT community and I'm more than willing to talk to you off-line as it were. (((Hugs)))