I cannot imagine the pain you are going through but I can understand it. And for those who try to deny and say mom or parents could never do that to their kids, I say, hell then can. There are tons of parents who mistreat their kids. They show their preferences among siblings and even make it known. Having a kid is a choice made by the parents and they should provide as much love as they can and equally to their kids, no matter how many of them they have. These kinds of parents cannot feel the pain of the less loved of their kids. And the worse of all, when a kid less loved by his parents talks about it to his siblings, they all deny it and to some extent call him crazy for making things up.

In you case, what do your siblings say? Tell them how you feel to see if they will talk to your mom about it. If it stays the same, you should just move on. I understand it is very hard for you as you love your mother a lot but at one point you have to start ignoring her. You cannot let yourself be hurt all the time. Good Luck.

Man this story sounds so familiar.