Check out some things first before writing it off. Do you have title to the time share interest? How much did you pay and how much did he pay? What was the total purchase price? What is the current market value of the time share interest today? If there has been appreciation, you may want to ask for a liqudiated investment value.
You can ask for repayment of your money alone or that plus appreciation equity, if any. Let's say the cost was $5000 five years ago and today the time share interest can sell for $10,000 on the open market. If you both paid half then you have a $2500 paid-in amount and another $2500 equity in appreciation. There may be some offset expenses such as maintenance fees etc. So you make him an offer for him to buy you out. Of course this scenario will not work if the property did not appreciate. If he refuses to buy your interest you can take him to Small Claims Court as long as the amount that you are seeking is less than the threshhold ceiling limit in your State.