[Kakorrhaphiophobia]

Hey Nick,

Your family sounds like what I'm living through, sort of, minus the grandma and add in two cousins and an Uncle...
The only ways I've found to deal with this situation are to use avoidance, even if it ticks them off, avoiding the negativity is the best option because you can't let them get you depressed all of the time and try and find some other person or people to vent to and talk to, try talking to a doctor or friends.
Keeping everything to yourself isn't going to get you very far because everything just piles up.
I think you going to college will be a big change, but it will be for the better. It will allow you to get away from your mom and grandma and help you be less stressed and have more freedom.
I think you should hang out with your sister more, even if going on a walk seems to much, which at times I understand it can, you really should do that for yourselves. Getting out and walking is kind of releaving, it allows you to get fresh air and sense your mom and grandma most likely won't be near you both when you're walking, it could be a good time for you and your sister to talk and discuss things happening around your home and a time when you can sort of help her if she needs you or when you need her she can help you.
My cousin and I do this from time to time because we go absolutely nowhere else most of the time and walking is our only way of getting out and talking without anyone else hearing us or knowing we're talking about them or venting about what's going on.
Try and help them out as much as you can, even if you don't necessarily want to and if they don't really notice or care at first or at all, just the fact you're doing something for them will make them feel happy even if they don't show it.
I hope I've helped. If you ever want to talk or need any advice, you can PM me and I'll be glad to help or just chat.
Good luck and take care.