[UPDATE] My [31/M] Mom [54/F] and my sister [32/F] hate my girlfriend [29/F]

Well first off, here is the original thread:
https://www.reddit.com/r/relationshi...r_32f_hate_my/
So, like it said in the thread, my sister wanted to talk to me that night on Skype. And just like I figured, she saw the room in the background and the first thing she said was, "What are you doing at her house?" I tried to tell her that I don't think of it as "her house." I think of it as "our house." We both lived there together for 5 years. Both of our names are on the rental agreement. It's not "her house."
So after that I didn't have to say much. She knew we were back together. And she went off on me. She went on a tirade about how I was finally starting to show some improvement. What was I thinking? She should have know I was just going to screw up, etc. And this was all on the computer when my girlfriend was home. It was in my native language, so my girlfriend couldn't understand it. But she could tell it was a heated conversation.
She asked if everything was ok and I shook my head and told her I would talk to her about it later.
So then, I'm not even off the phone with my sister for a half hour, and my Mom starts blowing up my Facebook messages, basically saying all the same stuff my sister already said. But of course she added that her and my dad always expected so much more out of me. I could have really did great things with my life, but instead I decided to surround myself with bad people and live a ****ty existence.
My girlfriend saw how upset I was by all of this and did what she could to help. But I really just needed to be alone for a while so I went out driving around for an hour or so.
So... basically over the last 10 days or so, what relationship I had with my Mom and my sister has pretty much unraveled. They both told me that it's basically her or them. Well, in my opinion blood is not always thicker than water. You can't choose your family. My girlfriend is the one who was in the hospital sleeping on a futon when I was recovering from my suicide attempt. My family wasn't here. My girl helped support me while I was unemployed. (Yes, I have a job now.) MY girlfriend was my rock through a lot of hard times. Yes, I did lean on my sister a lot too. But my sister clearly doesn't care much about what makes me happy.
I don't know if this means my Dad and my brothers won't talk to me now either. I guess I will find out.
To me this seems so petty. I just can't understand how they could be this way. My sister and I aren't even a year apart in age. We were best friends growing up. Does that mean nothing?
And neither of them can even tell me what it is they don't like about her other than that she's just "not good enough." And they both have said I could do so much better. I would love to know what they're definition of "so much better" is.
So, that's what happened if anyone cares. Any comments or advice or support is welcome. Thanks.
TL;DR My Mom and my sister have pretty much disowned me because they don't like my girlfriend.
EDIT: Wow, I just want to thank everyone for the flood of support and encouragement. I am trying to get through every comment before I have to leave for work. This has really helped me see that the problem isn't all me, as I was lead to believe by them.


Source.