why can’t i stop obsessing about something i can’t change?

i feel like i hate my brother. he behaves in ways that hurtful and inconsiderate. he isn’t bothered by his behavior or how it hurts others. my sister is able to not fight with what is and maintains her joy. she spends 0% of her time thinking about him. I, on the other hand, spend inordinate amounts of time thinking about his, getting mad, wishing he wasn’t who he is, feeling bad for my parents and kids, our entire family…this puts me in such a foul mood and I waste time and energy that can be spend on creating the life I want (or the 1,000 things on my to-do list). How do I stop obsessing about this? How do i discipline my mind to move away from this?

So grateful for this community.