WIBTAH if I stopped co-parenting with my mother?

I’m a college freshman (18f). I go to school about 3 hours away from home. The past 3 years I’ve been parentified by my mom. After she left my dad, she wants to treat me like a husband not as her kid. She’d complain about all her issues to me instead of confiding in a more age appropriate person. TMI but she literally told me that my dad gave her stds from cheating on her.

Along with this I also did a lot of parenting while she worked. I have 2 younger siblings that I put to bed, took to school, made sure they did homework, and sometimes cooked meals. I was also expected to take care of the house. Which meant I was cleaning and having to parent my siblings so they’d actually help.

This was all fine and dandy until the summer before I left. About a year ago my older brother (who is our elderly grandmother’s caretaker) bought a ps5. Our grandma doesn’t have WiFi so he left it at our house. Over the summer, my mom decided the best way to parent was letting my little brother (9) have unrestricted access to this PlayStation.

This unrestricted access has turned my brother into the spawn of satan. He screams, fights with my sister(13), bangs things on the ground, and is incredibly disrespectful. His grades have nose dived. (All A’s and B’s to straight C’s) And about a month ago I got a call that he and my sister tore my door off the hinges fighting. Over thanksgiving he also obliterated his phone by being careless and tossing it around.

This morning was my last straw. I got a text that my brother has been bullying people in his class. All 3 of us older siblings have been bullied. We’re poc in a southern small town. So that kind of thing is not okay with us. My mom expects me to come up with a magic solution to fix the monster she created but idk what she expects me to do. He’s not my kid. I didn’t ask to raise him. I don’t want to raise him. I’m done trying to give advice to my MOTHER on how to raise HER kid.

Would I be the asshole if from now on I ignored my mom’s attempts at getting me to co parent from college?

Edit: I should mention finances because it may be relevant. My mom is well below the poverty line. My dad makes over six figures. So I couldn’t talk to an attorney because my mom who we stayed with exclusively during the court process, didn’t have one. She also couldn’t hire any help because we were/they still are living paycheck to paycheck