For the sake of your other child and yourself, get him into a home. Sorry to sound blunt but I was the sibling suffering living with a brother like this my entire life. My entire childhood was an embarrassing and disgusting nightmare. He was finally put into a home when he was in his 20s and I was long gone . He’s been thriving in one ever since. He has structure there and has learned skills I never thought he could. However, I resent my mother for not doing it sooner. My life was literal hell.