You are on the right track with the first item. You'll probably want to get an antiharassment order, which you can file at the Maleng Regional Justice Center down there in Kent. After you file, there will be a hearing with all parties and witnesses present. I know it sounds silly, but it helps you legally to make it explicit that neither of you want to hear from her again, that all contact is unwanted contact.
Second, there is a cause of action in Washington for intentional infliction of emotional distress, but it's a very difficult one to prove harm for because your only harm is emotional, as opposed to physical injuries, which are more easily quantifiable. Additionally, the defendant's conduct must be extreme and outrageous. Though this is understandably traumatic and troubling for your family, it may not be enough for this cause of action. With more details on your case, an attorney could more easily determine if you have a case that is worth your time to pursue.
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