My brother is the favorite child and it's destroying me

I'm in my 20s and my brother is finishing up high school. Our parents split up when he was a toddler and I was finishing up elementary school. I was always closer to my dad but he had a lot of mental health issues and he couldn't be around as much for us when I was in middle school and my brother was very young. As a consequence, my brother feels very let down by him, which is understandable. The problem is, our mom completely enables my brother's behavior. He's very high achieving and naturally clever so doesn't have to work very hard and got great results in school and will be going to a top university. Our mom is not a native English speaker. We were with relatives recently and she made a joke about how even though I work really hard to speak her native language (which she didn't speak much of when we were growing up), my brother has more of a natural aptitude for it. I wanted to cry. I'm not naturally as talented as him but I have worked very hard and am in grad school on a full ride. The other thing is, since our dad isn't as involved in my brother's life as he was in mine, my mom has made up for this by giving my brother whatever he wants. New gaming PC, king size bed, making the living room into an office for him, which means I have to sleep on the sofa and get woken up by him when I am at home because I don't have a bedroom. He completely rules the roost. He's lazy and not very nice. When he finishes a drink from a water bottle, he throws it onto the floor. When he showers he leaves the entire bathroom floor soaking wet. When we went on a family holiday, we shared a hotel room and I sat down on the edge of his bed to change my shoes as it was the closest to the door. Without anyone seeing, he kicked me so hard off of the bed that I cut my arm open on the frame and then laughed and said I had fallen over. He pinches and kicks me and he is now physically stronger than me. Then he wants to be nice and asks me to play video games with me and hugs me. I literally don't know how to approach him because his moods change like crazy. But my mom is so proud of him because he is so good at school and is popular with everyone so she barely disciplines him. I have my dad but he lives in a one bedroom apartment and I can't really stay with him. I just feel so sad that it is so obvious who her favorite child is and how she has let him become a spiteful bully. I want to have a good relationship with him but his moods are all over the place and he knows he can get away with anything. If he ever hears a criticism that my mom makes of me, he will dig it in like a knife. He has no empathy and genuinely thinks he is God's gift. I just don't know what to do.