Your statement describes a situation where you might have a cause of action at civil law for slander, libel, and defamation of character (provided the "awful" things are not true.)
[In accordance with the Avvo community guidelines, this communication does not constitute "legal advice", nor does it form an attorney-client relationship.]
You may be able to get an anti-harassment order if you can prove a pattern of harassing conduct.
The information is for general information purposes only. Nothing stated above should be taken as legal advice for any individual case or situation.
I'm so sorry that you are having to go through this nightmare with the abuse from your mother dredged up again after you thought you had escaped. An anti-harassment order may be useful, or it may just encourage her behavior more and our courts/our government agencies are very reluctant to impinge on the freedom of speech of any citizen.
It seems to me that your better course of action is to warn people who may come into contact with your mother that she is hostile to you and recommend that they ignore her. If there is another responsible person in your life who your mother might listen to, you could ask them to intercede for you and ask your mother to stop hurting you. I don't think courts are the answer for everything or that they would be likely to help you much with this problem.
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