Statute of Limitation in NC

After going into business reluctantly with my inlaws...we i dissolved business relations with them in 2006. My controlling father in law made claims to my husband (because of other abusive issues we were having with him) that we owed him for everything he had ever bought for him..right down to my husbands first car. Out of frustration my husband added in his head an amount that his dad had spent on items such as his first car, help with college and part of our business expenses. This check was written in 2007 and never cashed. We recently had to take out a 50C restraining order against my father in law due to harassment and physical and emotinal abuse...we won the restraining order. Just 3 days ago, Sept. 10, 2010 we received a letter along with the copy of the check written in 2007 saying they had made recent attempts to cash the check (we no longer have that account) and that we have two weeks to pay this debt or they will seek an attorney. As crazy as it sounds..do we have any defense since they have this check. There is no contract and the business relationship was dissolved professionally.