If someone is born into a family of abusers, but is the only sane one...?!

You should find someone you trust to talk to about this situation. A school counsler for example or another family member that you can talk to and confide in. This does not sound like a very good to have to deal with. First...This has nothing to do with you they are the ones with the problems. Second...it is possible that they may have a mental health issue(don't get wrong I'm saying they are crazy or anything like that it is just the catergory that this type of behavior falls under). Third.....it probably be beneficial for you to speak with a Therapist to get all this out and have someone to help you cope. Fourth......You are not cursed. You just in an unfortunate situation. Fifth......why God does what he does we do not always understand but some day we will. Think about this.."God will never give you more then he thinks you can handle"...There is a reason you are in this situation. I can't tell you what it is but someday it will reveal it self.

There are millions in situations like that. God expects us to learn from the hardships; people who have no hardships learn little.