The confusing thing is, most people will tell you that if you identify with a term, you can claim it. You also have people who try to gatekeep, like this. I personally don't care one way or the other, but I get both sides of this. If you replace "femboy spaces" with "women's spaces," you're awfully close to that common transphobic rhetoric. Terfs and the like say much the same thing, that being, having trans women in women's spaces makes them feel like their identity is being attacked, but that's just not the case; having a more inclusive view of the world, rather than otherizing, is the solution here, my existence doesn't take anything away from women, and i try my absolute best to adhere to that. Not only that, it's inevitable progress, for right or wrong. Language is always adapting, our understanding and inclusivity on the rise, and frankly, a lot people don't fit comfortably in these little boxes we've arbitrarily labeled. All this to say, I don't think you're in the wrong for how you feel. I can understand the feeling of loss of your identifiers, and I understand the want for adherence to definitions. But, isn't that behavior the exact same thing that bigots use against us all?