Brother bizzare behavior..drinking? drugs?

My Older brother who is 25, i am 14, he has been drinking and smoking pot for a very long time, since about my age of 14. He recently told me he has tried other drugs. Last night He came home at like 1 am and dropped his car off and took my moms car. BTW he still lives at home. My mom woke up early this morning to go to the store. As she left to leave she saw her car was missing. She thought it had been stolen, but my brother took it. When my mom and dad tried to talk about it with my brother he was very aggressive and talking like a "gangster" when he is not, at all, he was just screeming at her. My mom was afraid of him, and my dad wanted to hit him. He has been very aggressive to me too, he was twisting my arm and wouldnt stop, i was afraid it would break. He refussed to tell my mom where her car was and why it was there, but he took her to her car. then he forgot the keys at home and went back to get them, he left to go get the car again with out my mom and left his car there. He told me what kind of drugs he has tried and some are pot, crack, cocaine, and shrooms. He is worrying me and my whole family and we dont want anything to happen to him. but this is becomming out of control. Please what does this sound like to you?