I can't keep living with HD mom

Hi! I've been lurking this subreddit for a long time, trying to find answers or help. I didn't want to feel alone. Today something snapped inside of me. Every important day or even normal sucks. Since I moved to different city to uni I feel much much better. I came home for christmas and today is special day right? It is totally destroyed by my mom. She is getting worse and worse. Since I see my family once/twice a month I can see it very well. She keeps coming to me and my brother room talking stupid things. Asking him to give her clothes so she can put them in closet. He is not going to sleep right know so I don't know. It is a drop in the ocean. I love my family and I like coming back home but I guess I can't come here. It is too much for me. It's following me since I was 14, now I'm almost 21. I feel bad for my younger brother and dad. He barely keep it together. He doesn't sleep home anymore because no one can stand being near my mom anymore. The worst thing about it is that no one can truely understand. Except people from this subreddit I guess. Sorry for chaos but I'm very angry and sad and everything... When she makes me angry I say stupid stuff and I feel awful. She keeps coming to room talking all the time to my brother or me. I'm trying to protect him at all cost. I can tell her I'm going to use force and she doesn't care. No matter what I say she doesn't even care. All she cares about is having candies and sweet drink. She keeps collecting them. Example 4 bottles of pepsi and 3 of juice. Sometimes I just can't stand it anymore. She made my teenage years awful. She destroyed every of my birthday, every christmas and every important day. She doesn't understand a single thing. I just wish she would be in some special place and someone would take care of her but it is not possible. I just don't know what to do. I don't want to test myself but if I had to live like that, I'd rather be dead.