AITA for refusing to hand over my college savings to my estranged mom?

Hello, I posted this on college life and got very mixed reactions. I'd like to hear your opinion.<br><br>My mom had an affair and cheated on my dad for years. She got pregnant and moved in with her new man, and a year after that she dropped me off with a suitcase at my dads and never looked back. She sent me a birthday card with $50 on it every year (I didn't know this until I found them all in my room) but never contacted me, never visited, never called, never sent a text, nothing. It was as if I didn't exist to her. The only reason I found out that she was even still alive was because my dad had to deal with her new husband to get his pension from his old job. The man was making all kinds of demands, so they had to contact her. It was very emotionally draining for me because I had thought she was dead. I was just 9 when she left.<br><br>Fast forward 10 years to last week. She called me and said she wanted to talk to me. I was surprised because she always said she didn't want to talk. I asked her what she wanted and she said she was in a bad financial shape. That she had spent her savings on my brothers college and now didn't have enough to pay for my other brothers. I laughed and said that I wasn't going to give it to her and she said that I had a responsibility to help family. I again laughed and told her that it was hilarious to hear that from someone who had abandoned me as a child. I also reminded her that I was just a child myself and didn't have any legal obligations. She started raising her voice, and my dad came into the room, took the phone and told her that if she called again, he would contact the police and get a restraining order.<br><br>She then called my dad and said she was going to sue us for financial support for my brothers. She said that just because she didn't have a relationship with me didn't mean she couldn't have a relationship with my brothers. My dad told her that she was just trying to extort money out of him and that he was going to tell the judge that her children were just a means to an end. He then told her that she was making a big mistake because he had full audio recordings of our conversation, and he was going to play it in court. She hangs up on him, and then an hour later we get a call from my "brother" (he's about 6 months younger than me). He says he's been told about me and that he's always wanted a sister. He then says that he understands that I might not want to be involved but that his college is really expensive and he needs my help to be able to study. When I say no he hangs up the phone and his mom calls back crying.<br><br>Now I've been getting calls and texts nonstop for the last few days and my grandma even came to my dorm to ask me to give them just a little bit of money. I don't want to give them anything and I definitely don't want to give my mom anything, but I'm starting to feel really bad about my brother. Now I'm in doubt, and I was starting to wonder if maybe I should give them something. It's 10k so it's not nothing, but I do have a good scholarship and I've only spent 2k so far so I could do it. So AITA for not wanting to give them the money I earned?