Do I have a claim with merit?

Unprovoked, a former co-worker (whom I have not spoken tor 14 months) has slandered me to a mutual customer. Said former co-worker accidentally copied me on an email thread in which she made the statement to customer "you should drive straight through and beat her ass senseless. She is pathetic" I did not respond and forwarded the email to my managers. My company and former co-worker's company have a working relationship. My industry circle is tight and I am afraid of the repercussions to my reputation and career that may come as a result of this former co-worker's statements of slander and libel. To me, it is harrassment. I am considering a claim against this co-worker for defamation of character and libel. Does my claim have merit?