I know exactly what you mean too! When I was younger my older sister and especially my older brother use to pick on me constantly! I was their personal slave. They made me fetch them water, called me names, throw boogers in my food, beat me up, etc... It made me so sad too, but I looked up to my older brother so much. I wanted to be like him, dress like him and even style my hair like his. I tried to tag along with him as much as I could but he made me feel like a nuances and a burden.
Now that we're older, all in our twenties, things have gotten so much better. My family is more close with each other and have matured in alot of ways. Keep in though, my siblings still pick on me occasionally b/c I am the baby of the family. My brother spent 7 years of his life in prison, so it did make him realize how important family is. He once joked that he can't mess with me anymore because I'm so much bigger and stronger than he is now! hahahaha!
With your brother situation, maybe he still has some growing up and maturing to do. Maybe he needs to spend time in prison? Heheheheh, j/k! Sometimes people like that just need their own space and their own life. I just hope he realizes how important family is before it's too late. Don't worry, you're a great little sister. This just shows that you can love someone unconditionally. So be proud of yourself.