Any tips on dealing with a family problem?

If you are 18 or older, it is time to move out. I went through similar b.s. with my younger siblings. I am the oldest too. I used to take everything valuable with me to work or keep the big stuff at a friends house. All I did was sleep there until I got a place w/ a friend when I was 19. I am so sorry for you. I know how much it hurts. Take all of your valuables that you bought out of there ( no matter whose room they are in) and find a place to store them like I did. If you didn't buy it, leave it there. Start trying to find a place to live and maybe a friend to split the rent.