Can you get your hands on your lease or ask your real estate agent to send you another copy.. There is a clause in nsw that allows you to go to tribunal if you separate and then you explain you can't afford to pay that much etc.

And another about not being able to pay anyway, financial hardship, which would certainly apply when separating....

Contact the rental tribal on your state and ask or check out your lease clauses.... Good luck..pm me. If you need any more specific help