My (15f) dad wants custody of my brother (10m) but not me because I'm donor conceived.

My parents had me using a sperm donor cos they thought my dad couldn't have kids but then they ended up having my brother.
Now my parents are getting divorced and I wanted to live with my dad cos he's less drama than my mom but my dad decided he doesn't want custody of me cos I'm not his biological child, he only wants my brother. And now my mom is hurt cos I said I didn't want to live with her and she's sulking and just being so hard to be around and since my brother lives with my dad most of the time now its just me and her except for every 2nd weekend. I keep asking my dad for help but it's basically like he doesn't even care about me any more cos and doesn't see me as his kid. So now I'm wondering did he always pretend he loved me? Cos he always knew I was donor conceived. And he's angry with me that I keep calling him dad and asking him for help.
I feel like I made a huge mess of this whole situation and both my parents are mad at me and I don't know how to fix it. What can I do to make it better with my parents?
Tldr my mom hates me for wanting to live with my dad, my dad hates me for being donor conceived, I want to fix it.


Source.