Defamation Lawsuit

To summarize...an employee reported that his green card provided to me at the time of employment was false, I spoke to my employer and asked how to handle this situation and in the midst of discussing this to my manager another employee stated that I said, ".......". This employee has displayed that she obviously does not like me for personal reasons, however I have ignored finding no basis for her feelings and therefore no reason to harp on. This statement, however that I DID NOT say was told to countless employees including the President of the company. It was later told me all the chatter was happening about me around the office and that the President was furious with me as well as others employees being offended by the statement. However, I DID NOT make this statement NOR ANY OTHER STATMENT that would have indicated that I have a personal vindetta against that nationality especially being as though I am of that very nationality. However my direct manager has made these types of statements before and I beleive that the employee heard my manger say this and she instead is telling people that I said it. I approached the employee spreading this slander around and assured her that I did not make this statement and accusing me of doing so is slander and has been very disaterous to my reputation. The employee states that she will let go of the issue, however the fact remains that this slander has spread to other employees and regardless of me talking to them I am feeling the cold shoulder from those employees and from the President. I overheard the President say, "Once we have a reason we will let her go..." Now knowing about the lies that were spread about me I feel as though that statement was made in retaliation towards me and I am wondering if I have cause to pursue this horrible slander with a lawsuit.