Should I always come second?

Why is it that I’m always taught to think about others before myself? No matter what the situation is, if I take into account that I matter too, I’m selfish and irresponsible? As soon as i woke up today I felt like complete shit, today’s period day 1, and the first thing my parents asked me to do was make food for them and clean up all the mess everyone made last night, even though I came back from work pretty late. They didn’t say good morning or how did u sleep or did u eat or anything regarding me. They never do. It’s been going on like this everyday of my life and I’m supposed to be okay because im being helpful and respectful. Im always asked to do something for others and expected to not complain because it’s the right thing to do. But what is so right about helping people who have never given two shits about you. I know that other parents have endured a lot and sacrificed so much for their children, but not my parents. They didn’t even plan out having me or my twin, they were never ready to have kids and now they think that we owe them something to repay all the troubles we’ve caused; as if I’m a burden to them and need to be held accountable for something that was out of my control. I’m sick of people thinking I should come second and I’m sick of people treating me like I belong in that place. I’m out of here after high school since I’ve been saving up from my job and I love my family and obviously don’t want to leave them but I know that this is the best thing for me to do. To stay away from toxic people who only make me feel like I don’t matter.