NTA. Update us please

Unfortunately I'm an advocate for "Fuck them kids". But what I will say is he's acting out like that is not entirely either of your faults. Children can be evil and know what they are doing when they say mean things. He's your brother not your child. You're job is to not die and get through school so if he sees anything else it's how to fight through the first jungle in life. Spend time with you're bf. You don't just need space from your household or that demon child what you need is for everyone involved to get their shit together. When he gets older he'll notice if not sooner, that being mean pushes people away. I'm no doctor and idk if that works for everyone or every child. He should have his friends at school or on fork knife to fill his social meter but you not being there and occasionally popping up when you want to be seen sends a message to your parents that they sti have the both of you to care about....I think... lol idk I'm an orphan but i hope this helps. You're not hurting him directly or anyone and it's mentally safe for you. It was for me at that age.