I'm desperate, things are terrible. Sorry its so long.?

I don't know how old you are, but if you're old enough and can afford your own place, you might one to consider that option. It seems to me that you are stressed and need a break from everything and everyone. If you can move out, do so. Or go on a little trip/vacation and do some soul searching, spend some time with yourself. Do things that you know can relax you. As for your brother, he is your blood, so try to see if you can manage a normal, argument free relationship with her.