At this point, I'd get whatever money you can from her. But take the advice here and don't give her access to ANY of the site until paid in full.
Definitely take down the existing site and put up an "under construction" page. The "taken down for lack of payment" will add fuel to the fire and may create some liability for you. (Or, if you still want to embarass her a little bit, make the page say "Site opening on May 1, 2007" or whatever the original date of completion was.)