You can not help your parents and brother. You can not do ANYTHING about your parents' happiness. It is not your job. It is not within your power. As harsh as this seem, the sooner you learn this the better off you'll be. I am being blunt here, because it will not do you any good to mince words. These are the things I wish someone had told me. It's your parents job to teach you this, but lots of parents miss this crucial lesson. You can love your parents and your brother and still do what is best for YOU. That doesn't mean you love them any less.
You have absolutely no power in the situation, except over yourself. Student loans are not the same as other debt. No, you probably couldn't live by yourself, but you could live in a dorm or with roommates. Student loans can help pay for that. You are 19. Starting YOUR life and having it have peace and a good future is the best thing you can do for yourself and for your parents, too. If they can't give you the foundation you should have, I'm sorry, you will have to provide that for yourself. It will be worth it. Why delay?