Slander and defimation of character

Name    : 
E-Mail  : 
Subject : 

Comments:
: I have been accused of leaking "sensitive information" to people out side of my department by my former boss. She pulled a fellow employee into her office and firmly told him to stop associating with me because I am not to be trusted. He confided in me and express his concern because she made specific reference to me and said it may cost me my job.
: This is not the only person she has spoken to in this fasion about me. 
: I believe this to be defimation of character and slander. What can I do?