Hey,
I really don't know exactly what to say to make you feel any better about this. Sounds like you're going through some really tough things. As for people saying negative stuff about you, just remember that those words are meaningless unless you choose to let them mean something. Like, if someone said you were a mouse, that'd just be so ridiculous that you'd probably just laugh at them, right, because you're obviously a human, not a mouse. So, if people say that you're a freak, just treat that statement the same way: don't take it seriously or dwell on it, just brush it aside because you're obviously not a freak. Those people have no right to judge you, and you don't need to accept their judgment in any way.
Anyway, I don't know what to tell you about your family, but you're right, you should be there for your sister. And don't just live for her; live for you, too. Don't give up on yourself. Life is hard, but you gotta keep in mind that no matter how difficult it is, you're stronger than all the problems life throws at you. One day, you might look back and say, "Wow, those were some really hard things to go through. But I'm glad I didn't give up, because look where I am now." And if things don't seem to get better, just keep at it anyway. Do what you can to make things better, instead of waiting for something to happen out of the blue.
Even if things don't get better, you can make it better by the way you perceive things. If you look at everything in a negative way, then even good stuff isn't going to seem that great. But if you focus on the good things in life and in working towards what you want in life, then the bad things won't seem so bad, and you'll be able to deal with them better. Find something that makes you happy (or that used to make you feel happy if you are depressed enough that nothing seems to make you happy) and focus on that.
I'm not too good at giving advice, but I hope that helps at least a little bit.
