You may want to have her buy you out.
Figure out what the house would have to be priced at to sell quickly, in a depressed housing market. Deduct all of the real estate commissions, transfer fees, etc. Take 1/2 of that remainder amount(which would have been the $$ you guys yield had it sold it outright), and that is the amount she could pay you. Decide whether you want to float her that loan. If the price is right, get it all well documented.