Do you think my mom is showing favoritism?

I always felt a different treatment between me and my younger brother that is eating the realationship between me and my mom. When ever my brother was responsible for some form of misbehaving or wrong doing, my mother would blame me for "letting him". At fist when these instances took place when we were younger, I knew she would say something like that, but now that he's older, I'm getting worried. Today for example my mom barges into my room and screams at me to search the lost cordless phones, automatically thinking I did it because I am a teenage girl who "talks alot" despite my lacking social life. I tell her that I saw my brother on the phone for 4 days straight. She reprimands him, but screams at me for "not telling her he had them". I was devasted. There are millions of situations such as these that have been going on for years, and it's making me feel like something less. As a 10 year old, when my brothers ADD kicked in, it got to the point where I wanted to kill myself even at that age. My mom was the youngest growing up with two older brother just like how my brother is with me and my sister. I think my mom feels a connection with him for a few reasons: he's the youngest like her, and her only son who has ADD. I have clinical depression and has been told on few occasions by her that I'm not wanted in the house, it's happier when I'm gone, and if she could, she'd send me to military school. I'm not a bad kid, I don't cause trouble, and I've been quiet all my life. Yet my ADD brother who can't shut up, clean up after himself, treat his friends nice, or be remotely independant at his age is looked to as "perfect". My brother doesn't even have any chores like I did when I was his age. Even when I was younger then him I had tasks that required taking care of him, when I needed to be taken care of too. My mom has made it clear even through words that sometimes she wishes I was gone....