At 18 you can leave home. And, you can enroll wherever you live. If you do leave home, please do continue in school. You will not be hurting your parents to drop out but you would be hurting yourself. Good luck.
Although I have answered the question to try to help you, you should consult with a lawyer in your area in person on the matter. In addition, my answer does not establish an attorney-client relationship between us.
Yes, at 18 you are allowed to make these decisions for yourself. As Ms. Henley notes, continue with school and do your best to "show" your parents by succeeding in life. Get an education, work hard and some day learn how to be a family again, if necessary.
Good luck to you.
Although my intent in answering this question is to aid you in the legal process, my answer does not establish an attorney-client relationship in any way. You should seek the advice and counsel of a qualified attorney in your community to evaluate your legal needs and to advise you. No Attorney-Client Relationship is created without the specific intent of both parties.