G, you are quite simply a gem. It sounds like both you and your boyfriend are the textbook example of how to make this work. He told you early in the relationship and although you have some doubts, you are clearly making a serious effort to understand. My advice is don't go to fast and be true to yourself. Obviously, be as accepting and as supportive as you can. But, I believe your bf will understand if you tell him at any point that you need to slow down. That is better than becoming resentful.
You also mentioned kids. You can find some threads on here about "whether or not to tell the children." There is a variety of opinions, but my opinion is if he is not transitioning, there is no need to tell young children. I have two daughters, ages 8 and 11, and we have decided not to tell them at this point. However, we have raised them to be accepting of all people, and they have seen me in drag a few times (charity drag shows and one Halloween). Thus, our hope is that if/when we tell them, it won't be a big deal.
Wishing you all the best,
Jamie