It's great that you're getting treatment because a sane (for lack of a better word, b/c I don't mean you're insane) person wouldn't consider suicide. It is a permanent solution to a temporary problem, and suicidal thoughts often come when a person has been depressed for a while.

In reality the only reason to stay here after you're 18 is because you want to; if you wanted to leave badly enough you would. But if you have the strength of character to want to improve yourself, you have the strength to make it through this ordeal, because this is about your life, not your parents' and not all the ones who come after you. You have to make the decisions that are right for you.

(Not to say you have to be completely selfish and abandon your family, but don't make decisions purely for fear of the consequences on other people. Relax! You only live once.)