Brother getting out of rehab tomorrow. What should I expect?

Tomorrow my brother (M32) is getting out of rehab bc he went on a huge drinking bender and scared the shit out of my family and I. He has always had a bad relationship with alcohol. He lives on his own with an older male (46) roommate, who doesn’t drink, not too far from us just 1 city over. My mom had told me he wasn’t doing so well so we paid him a visit. When I tell you…. When he opened that door to greet us, I did not recognize the creature that opened the door. It was a skinny, dark eyed, sad little person who opened the door. I immediately saw so much pain and sadness in him, it broke my heart. It got worse from there & the past 3 days he kept drinking. From the moment he woke up to the moment he passed out. No food no water. He started hallucinating that someone was after him and started to get physically violent with us. Especially with my dad. I had to call the cops on him because he was literally going insane. Im talking crazy mood swings where he would get physically violent with us, and then apologize profusely minutes later. I feared my families safety.. I’m not too sure how rehabs work exactly. But he went in to detox on Friday morning and my mom called me today to tell me we’re going to pick him up Tuesday morning. I feel like he needs much longer to get help. He needs a therapist, he needs medication, he needs more. My parents are way too kind and patient and it honestly angers me that they aren’t tougher on him (it’s been this way all my life) ever since I was a little girl I felt like I had to be the “strict” one with him and tell him like it is, and be the bitchy little sister in a way? Instead of babying him and walking on eggshells. I don’t feel like the way he treated us deserves coddling and babying when he’s out. Drunk or not, he truly traumatized me and I feel so so so bad for my parents bc I know they’re worried and stressed.

Anyway.. thank you for any thoughts or opinions. Has anyone ever gone through this?