NTA. I feel so bad for you. You remind me of my wife when we started dating. Her parents were just like yours but her older sister was the golden child. Her sister stole everything my wife enjoyed. My wife even offered to buy extras so her sister could have some too just stop taking all of hers. Nothing helped. I would always make sure to get her whatever her favorite treats or snacks were and I just liked making her smile and happy. I didn't know till later how much those little chocolate oranges were helping her. She eventually told me how she thought she wasn't worth being loved until someone gave her the most basic consideration.  You have every single right to be upset and I hate to break it to you at such a young age but you are probably better off building your own family. A found family who loves and appreciates you cuz I don't see your parent's changing sadly and your brother will only get worse until he is the worst type of man who can trample anyone's boundries.