Brother Is Creepy And Disturbing

My brother is 24, and I have a twelve Year old sister, almost 13. He has severe mental health issues. Anger, depression, autism that makes him do really out of character things that are just… gross and odd.

He pees in bottles instead of going across the hall to use the restroom, and when he doesn’t have them, he pees in bed or on his bedroom walls.

He has multiple sex toys, and a life size sex doll… he has stolen her USED UNDERWEAR (panties with discharge, bras with her perfume on it) And cut her favorite shirt she wears and ties it around the dolls body. When confronted about it, he SCREAMS in anger at us, and tells her that he will “give her the money to buy more clothes” and to “stop telling (BIL NAME) I’m a pedophile”. He is a creep. I don’t want to know what he is capable of, but I know what he can do. I have been sleeping in her room because she is scared, and my mother won’t do anything about it because she likes him paying for her things. She also has brain damage that affects her memory, and cognitive functions, possibility early dementia signs. My other two sisters aren’t doing anything to help besides take her out of the house to do things and spend the night at their house. For context, I don’t have a house. I’m homeless due to DV, and financial abuse from my ex partner. I am on section 8 housing list, with a new job I start by the end of this month. I have BPD though, and other trauma induced mental illnesses. But if one of my sisters don’t take her in, when I get my house, she’s coming with me. I’ll make it a legal obligation. Idc what bridges I have to burn to protect her.

But what can I do in the mean time while I’m in a DV shelter?

Summary: brother uses 12 year old sisters used underwear on his sex dolls, how can I protect her while homeless and also mentally ill, waiting for housing and to start work? I can’t get a place set for me until six weeks after I start my job.