any lawyers on here...need help

my best friend was hanging out with this guy and she made it clear she only wanted to be friends and he wanted more ( a relationship) well she kept saying no and he said he was going to call her job and tell them all this stuff...well we go onto craigslist to find that he's posted 2 things about her. It states her full name and where she works saying shes a drug addict and how can 'you people' ( meaning parents of the kids) have a person like that working here ect-i printed these things out. The thing is, shes going to school to become a teacher and if lets say a school district were to look her up and find this..well she would not be getting a job. Shes extrememly upset-this guy wont leave her alone and now hes getting in the way of her job and carreer. Would she be able to file a lawsuit against him for slander? What should she do????? PLEASE HELP!