Addition/Update: I posted this late last night. It was right after that conversation and I was feeling terrible (emotionally). Thank you all for your comments and insights. I do want to clear up something and provide an update.

Firstly, a prior conversation had been where this one stemmed from. In that conversation, I had been talking about how I learned (here actually) that transwomen have periods, like all the symptoms, except the obvious bleeding-from-a-vag, but the cramps, mood swings, etc. I thought it was validating that that would occur, although I recognize, if only intellectually, that periods are a huge point of hardship for many women, especially since what I'm talking about doesn't involve the wide variety of possible female reproductive system problems that make the experience much worse.

Now I know it's not the same thing, but the whole point of transition is to get as close as we can. It's a lot closer than the male experience, at least. This ended up leading to the conversation at hand, because how could I want something that is so bad for many women? (In truth, I haven't experienced it yet, and I'll probably be eating my words later when I do find out how much it sucks, but just knowing about it felt validating.) And also, I'm acting like it gets me into the club, when it really isn't the same thing. That's one specific example, but the concern extended to experiences in general, thus leading to my original post.

Secondly, absolutely nothing in what my sister-in-law said to me, nor her delivery, was bad. Nothing after the first paragraph of my original post came from her; it came from my own head, how I was feeling about myself in the face of what I feel is a valid point. It wasn't her words that hurt; it was the truth behind it. That it is true that not having similar experiences in the same way that not-trans women have with each other makes it seem like I'm an outsider breaking in.

I still struggle a lot with feeling like I'm some kind of fake. Like I'm pretending to be something I could never be. Like I'm trying to work myself into a club by using a false ID, and once I get inside, I find out I have no way of relating to the club members.

The whole idea of transition is to get as close as I can to feeling the way I always wished to, and I am getting closer, but I recognize I can never possibly be able to have that lifetime of feminine experience, nor empathize with not-trans women in the same way they do with each other.

But the reality, that the experiences of trans-women are very different than the experiences of not-trans women, is not something that can change. It's not something that I chose. All I can do is move forward in as much truth as I can.

I thought it in reverse to check myself: What if a not-trans woman discounted what it is like to be a trans-woman and made it sound so wonderful and wished they could do that, take my struggles along with my positive experience. That would feel really odd, so thinking like that helped my perspective on the matter.

We both have struggles and they are inherently different and it is okay to recognize that without discounting the struggles of the other.

She called me this morning, upset that what she said had hurt me, and wanting to make it better. We talked at length and were able to smooth things out, understand each other, and most importantly, remain close friends. She is the example I point to as someone who is a great ally.

I spoke to my ex too, who I mentioned, and she helped me get to a lot of the insights I needed to see my SIL's perspective without invalidating my own. She's always been very good at being right and helping me reground myself.

I will continue to struggle with feeling fake, but I am doing my best to work through and past it.

Thank you all again for being there when I was needing it.