My electricity and water charge used to be included in my rent but my landlord has decided to charge me both separately from the rent. I received a note from her today which just states that she had received the electricity bill and my half share is $80.00. Is she not supposed to actually show me the bill or make a copy for me so that I can ascertain for myself whether she has billed me correctly?

Ask her for a copy. Do you have a lease or other rental agreement? She can't just change the terms.