Roommate Issues?

I have a roommate that has become completely impossible to work with. She runs up the electric bill 24/7 and has money to burn but always acts as if she's broke. Nothing is sacred (be it food, space or mail), she acts like a parent (though is 2 years younger than myself) and is completely condescending when I try to compromise with her expensive habits. In addition, I do not have access to our bills (she moved in first and has online bill pay) and she will not give me a statement. I'm either breaking my lease at the end of May or getting someone to sub-lease it. Since there is no satisfying the crazy roommate of mine I was wondering if there are any tricks to ignoring or getting over the mounds of money and sanity she's costing me. Anyone have suggestions to dealing with a roommate that hasn't grown up yet? I've been patient for 6 months and I just need some new tactics.