First times...

I never thought this would happen, but last night, for the first time in my life, I slept with my bedroom door locked. In my house we hardly even close doors, let alone lock them. But apparently, this is what things have reduced to. Not only do I sleep with my purse next to my bed and hide my car keys, but now I lock my door. Why? Last night as I was lying in bed watching TV, I heard my brother in my bathroom, which is right next door to my room. He's been in there several times in a short period, which makes me wonder. It's been happening like that more and more within the last two weeks or so. Anyways, I hear something fall and I knock on the door to see if he is ok and see what he broke. Instead, I am immediately hit with the odor of vomit, and not just any vomit, but drunk vomit. I asked him is he had been throwing up and he said no (as he wiped his chin), and then I asked if he had been drinking, and he angrily replied that he hadn't. Never mind that his eyes were glossy and he was slightly slurring. I work at a bar! I know what drunk looks like. He went into his room and locked the door (suspicious). I went to use the bathroom but before I could get anywhere I stopped as I stepped into a small but slimy puddle of vomit. Yeah, ew. I knocked on the door for him to come clean it up and he tells me to F*** off, more or less. So I called my mom and she came upstairs, confirmed everything, including that she had found more empty bottles he'd stolen. He came out of his room, saying he shouldn't have to clean up he vomit (!) since my floor was dirty as it is. I didn't realize vomit was ok compared to a few hairs in the corner. He'd also puked in the bathtub and on one of my shoes. I cleaned that up, as my brother got more and more belligerent. My mother told me to go to my room and lock the door and go to bed. I did.
Yet the whole time, all I could think about was how low the situation has sunk. I was also scared of what my brother was doing behind his on closed and locked door. Things are ok today, or so they seem, but who knows how it will be tonight. I'm scared, really.