AITA for asking my mom to pay me back the 15k I spent on my brother’s medical bills?

So I’m 22(m) and I have a brother (30m) I love him a lot, he’s a great guy, but he has very serious health problems and I’m not exaggerating when I say he’s seen close to death more than half his life. <br><br>When I was 16, I had to get a job, not because my parents wanted me to, but because they were in a bad place financially after paying for my brothers surgeries and treatments, and everything else. <br><br>So the money I saved my senior year in high school was spent on my brother’s medical bills, I saved around 15,000ish. <br><br>When I turned 18, all my savings was gone, again, on my brother’s medical bills. <br><br>I got a new job, and I worked that and a second job for the rest of high school. <br><br>I ended up saving $15,670 and spent it all again on my brother’s medical bills. <br>When I turned 21, I was in debt around $3k because of what I spent on my brother. <br><br>I’m currently in college, I got a new job and a second job, and I’ve saved $15k like I did last year. <br><br>My mom saw the money in my account and asked me to give it to her, I asked why, and she explained that my brother was in need of treatment. <br><br>I said no, I’m not going to give her the money, and she asked why not, I told her I don’t have any money to give her, and it’s not my job or responsibility. <br><br>My mom got mad with me, and said she spent her youth taking care of me and my brother, and she doesn’t have the money to pay for his treatments, and I’m being selfish and childish. <br><br>I said that she took care of us because she’s our mother, she had to, and I don’t have to give her the money. <br><br>She told me that she thinks I’m being an asshole, she said I’m being selfish and I don’t love my brother. <br><br><br>Is what I’m doing wrong?