I'm sorry you feel that way, Drake.
I stick to my motto "Things will get better" no matter how many times I've felt like shit, even to the brink of You-know-what, I just tell myself that things will look up and as far as I can tell, it's worked for me. Anytime depression sets in I just remind myself that things will get better, because they will.
Life always has its ups and downs, and as long as you remain optimistic, those up parts will come right back again.
During the low points I like to take some time to myself, do something that I really enjoy, like listening to music with the lights out or taking a long bath early in the morning before school.
The little things help immensely, in my experience.
If you feel like your brother is being treated better, you should talk to your parents about it, if they're reasonable adults then they'll try to do something about it.
I hope you can work this out, Drake.