disgusting unhygienic brother

i, 15f, have a brother 17m, who is so irresponsible and unhygienic. no idea if this is a common experience towards siblings, but my brother is absolutely disgusting and it's embarrassing me.

we live in a 3 story house and some people are in the 3rd floor renting. each floor has two bedrooms. now, me and him live on the second floor while our dad lives on the first. now, my brother reeks. he has this bowl of cereal that's been sitting in his room for 2 months, he's only decided to take it out a few days ago. the milk is absolutely SPOILED and the smell hasn't gone away yet. i don't know if he's desensitized from the smell, but he refuses to wash the bowl. he just sprays his smelly man cologne in the hopes of covering the smell up, which, fyi, makes it worse. the people HAVE to pass by our floor and it embarrasses me. they might think it's me. his room also smells like cigarettes. just imagine rotten milk and cigarettes along with him showering once a week.

we also have this bathroom which he cuts his hair in and i have to clean up the hair he cut. not to mention, it clogs the sink and the drain. he also takes these shits that clog the toilet and, surprise, i have to unclog it.

even though he's older, he had to get held back a grade because of some issues. we had the same classes 2 years, and he was so embarrassing. he had fights with other classmates, he had this messy backpack he cleaned in school. he even put his dirty socks inside which my classmates could see. it's all so embarrassing for me.

he's always done this, and i'm tired of cleaning his mess up for him. he literally turns 18 in a couple months and he lives like a pig. i don't want anyone in these comments to tell me to talk to him about it because he's convinced he's hygienic. he gets mad when someone calls him out, he threw things at me (heavy things, i got bruised on my face once) i was 12 and he was 15 because i called him out for this behavior. only my mom can say stuff about it but she's doesn't live with us. i can't take this. i need genuine advice. i can't just let the second floor go unmaintained but i also want to teach him a lesson. please help, reddit ☹️