Is a lien or judgement appropriate for this situation?

Before getting married my ex-spouse and I each put money in as a down payment to purchase a condominium. We put the property in her name and after 3 years of marriage she filed for divorce and refuses to repay the amount I put in as my half of the down payment. She said because the property is in her name and was purchased before our marriage she has no legal obligation to repay my half of the down payment. We are residents of Washington state which I believe makes the condominium joint property since it is a common law state. I would appreciate some guidance on the best way to handle this matter which would allow me to get the money back I provided for the down payment. Thanks.