Is AUTHOR wrong in the post ? POST : Alright guys and girls first post here so please don't rip me a new one if this isn't perfect. 
So before I get into this let me give you some perspective on the situation. (I'm being a little vague on some details to protect identity). Also this story takes place over 2009 to present. Hopefully it doesn't get to confusing. But I feel the context may matter.

So I am the older brother by a little over two years. My sister was biologically born my brother. We are from a small town in the states. When I turned 18 I moved out and started living in a major city. When me and my sister where the same gender we fought a lot as siblings often do. But after I moved out we talked and grew closer. I knew she hated living down there so I asked here to stay with me for a summer and got her a job where I work(this is all pre transition). She loved the city and we definitely grew closer from her staying. Well during one of these summers my dad passed away very unexpectedly. She moved back home with my mom, who needed the support. 
After a year or so I had a new place and made her the same offer. She gladly excepted and lived with me for about a year I think, can't remember the exact amount of time. I never really asked much, helping out bills when she could but that's it. During this time she met her now husband and eventually moved in with him. I didn't know they were dating or anything but the thought had crossed my mind. Not super long after she moved out she started telling me we need to talk. I had already seen some pictures of her dressing as a female, so when the conversation came up it was hard for her to tell me but I asked if that's what it was about. She told me she identifies as a female and is going to start hormone therapy. I told her none of that mattered she is still my family and I'm happy she was comfortable telling me. I try to be very loving and excepting after all we are all just people.
As I'm sure some of you may have experienced if you have spent you're whole life with some one and suddenly change names and pronouns, it takes a moment of adjustment. She was understanding and patient with me, as I was able to switch pretty easy but still made the occasional mistep. Anyways fast forward a year or so and she tells me her man proposed and they are gonna get married. Keep in mind my mom knows nothing of this transition. So of  coarse I spend a good long while playing middle man in trying to get my mom to understand her. My sister was very scared to have these convos and I truly believe my mom would not have gone to the wedding if I hadn't worked them onto talking with each other. 
My mom isn't as easy on the transition of her name and pronouns. My mom gave my sister her now dead name, and I was always close with my dad so I feel like that might be part of it too but I don't know. It just wasn't smooth. But she went to the wedding and had a great time and I felt overall it was a good thing. Like we all openly excepted my sister and loved her. The ceremony was gorgeous, I walked my sister down the isle and cried like a baby the whole time. I'm a huge softy hahaha. 
So let's jump forward another year. Me and my sister still talk and hang kinda frequently. And it's a major holiday so my mom comes into the city to see us. We spent most of the day together and my mom as usual was having a difficult time with the pronouns. She gets the name right for the most part. Also they don't talk allot so keep that in mind. And my sister can be pretty abbrasive sometimes. But me and her are really all my mom has in terms of immediate family. If it was up to her we would spend twice as much time together. So towards the end of the night my sister says I'm going home, it was wired cause I think a movie was still playing. She lives about 2 miles away and just stated she'd walk. I could tell something was up so I asked my mom to borrow the car so I could drop her off. 
In the car I ask. She states something along the lines of." I can't do it anymore I can't be around mom." I say "hey let's slow down. I think that would devestate mom if you did that." She say "your eather with me or against me on this, pick a side"
To which I replied "what!?, I can't pick sides your both family. I love you both please just talk with me"
I don't remember what else was said just the slamming of the car door when she jumped out, didn't even stop all the way.
And other than one Facebook message she sent me from when I tried to talk we haven't spoke in over a year. 
Now don't think this is the end. I spent the next few months just sendeing and her messages begging to just talk with no response. 6 months into this I got kinda drunk, and sent this(gonna copy from messenger)
"Listen I'm not saying that you owe me anything or that you have to be my friend or that because I was there for you that you should be. But like damn how is it so easy for you to just close the door on me? Like I just don't understand. Because I won't pick sides between you and Mom you just cut me off completely? Like I love you, I thought we were more than just family I thought we were friends. I am trying really hard to let this go, but it's just not that easy for me. To just be shut out for? for what? I've always loved and accepted you, I've let you live with me for practically nothing of asked nothing of you. And as I said it's not like I'm saying you owe me, because you don't. Like honestly you can read this and just look away and keep moving on with your life. But I need you to know like how much this hurts me. How much it bothers me. how much it's on my mind how many times I've written this message and deleted it. I walked down the aisle at your wedding. And we both cried together in the room afterwards. Like you don't want to talk to Mom it whatever like. But I'm not Mom. I'm your fucking brother." "
I've tried to give up but I can't. Maybe I'll just come knock on your door one day"
after those messages she told her husband that she was scared of me at what point he said if I showed up unannounced that he would call the cops on me keep in mind they only live 2 miles from me which is really what bothers me the most is we're so close together and she chooses to just ignore me. 
Anyways I know that was a lot to get through to get to where we are now which is she still doesn't talk to me and I don't really know what to do I've pretty much given up she's blocked me on almost everything. 
Am I an ass hole? 
Could have done something different or better?
It's something I think about almost every day and I don't really know what else to do.