Lets look at the big picture here. You mentioned she has lived off other people and has plenty of money and spends and saves but not on rent it appears.

Ask yourself, in what condition financially has this situation put you in? Are you loosing money with her as a roommate? Is she paying her fair share of food, utilities, etc?

If it's not financial resentment, is it that you work harder and she's getting off easy? Perhaps raising the rent (use utilities as back up) is the answer. If she balks, are you tip toeing around her all the time? I think you should be making a profit for sharing your home with a roommate.

Hang in there.