You need to speak with a criminal defense lawyer in Australia as soon as possible. I'm sure you can find one via the Internet. Good luck and let us know how you do.
Are you still in Australia, and can you make the court date? If so, Im not sure why this is listed as a RI question.
Call a local Australian defense attorney right away, see if they can accompany you to your court date and check on the local laws. Best of Luck.
This answer is for general education purposes only. It does not create an attorney-client relationship or provide legal guidance or advice. The answer is based on the limited information provided within the question and the answer might be different had additional information been provided. For legal inquiries all persons are recommended to consult an attorney in your state.
Good advice above - you need to consult with an Australian lawyer immediately. I have included a link to the Australian Bar Association's website; you should contact them for an attorney referral in the area where you are living abroad.
Refrain from making any statements about the incident unless they are to your lawyer.
I wish you the absolute best of luck in fighting this charge.
This is not legal advice and is not intended to create an attorney-client relationship. You should speak to an attorney admitted to practice in your jurisdiction.