It's your parent's place and their choice to enable or not. Sounds like, right now, they are into enabling. They too will need to find their own bottom to cease trying to save him from himself.
In the meantime, you graduate in 5.5 months, a blip in the long run. Your school, the libraries, Starbucks and lots of other places offer wireless communications.
You cannot change your parents any more than they can change your brother. Accept the situation as is/where and focus on your future life, in NYC.