Is it slander for my husband's ex to tell people I embezzled money from her?

My husband's ex has been telling people that I "embezzled" money from her. She even tells people I went to her bank (in another state) and posed as her to get access to her money. I haven't done any of these things! I have ben married to my husband for five years and I have never even met the woman. I have an email from her saying that my "low morales" have caused my husband to go astray and that she is going to sue me for the money I "embezzled". I am a hard working human being who has never stolen one penny from anyone. How do I get her to STOP!! She tells these same lies to her children and to anyone else who will listen to her.