We are a supporting community here on DU and we are ALWAYS here to lend and listening and compassionate ear. NEVER think differently. But in your situation what you need are supportive friends out in the real world. I know how hard it can be, I basically have none myself and it's made my life far more difficult than it should have been. But in my situation my parents, unlike yours, have been very supportive. They are also a good part of my problem but they have always supported me.
Since your parents and siblings ARE the source of your troubles you need to seek out someone else. Go out, try to meet up with like minded individuals. Go see a movie with someone, get in a book club, there are tons of other gatherings out there where you can meet a friend. You need to get your mind off what is happening and centre your emotional self around other people and other things. Find a hobby and immerse yourself in it so deep that it becomes a part of you, something you can take with you. I realize that these are all very worrisome real world problems but what you may not see if that your reactions to them are the problem, not so much the problems themselves. What is happening to you is horrible but you need to take yourself out of this situation and put yourself somewhere happier, hence the friends and hobbies. See if you can get to a place where the above begins to matter less, because at the end of the day even in the worst case scenario you still HAVE to live and doing so is going to necessitate these things, friends etc, all the more.
As said above if you are in a situation, financially, where you can get help PLEASE do so. Talking all of this out with a therapist can be very therapeutic!!