Your question was posted in the criminal defense section, but is really about civil litigation. Most civil statutes of limitations run 2-3 years, but I would not be able to hazard a guess as to which statute of limitations applies in your case. I suggest you try posting in the civil litigation section, or consult directly with a local, experienced civil litigation attorney.
With respect to criminal charges generally, WI has a 3 year statute of limitations for misdemeanors, and 6 years for felonies. Certain crimes may have longer statutes of limitations depending on the circumstances.
If you are trying to pursue criminal charges, you should contact the local police department/district attorney's office. They will be able to help you better than a criminal defense lawyer. Our job is to defend the type of people you are describing, not prosecute or sue them.
You can get a harassment injunction against her. There is a criminal offense that is stalking which is a felony and can be charged up to 6 years later.
In accordance with the Avvo community guidelines, this communication does not constitute "legal advice", nor does it form an attorney-client relationship. You should seek counsel in your geographic area regarding any specific questions.