Well this reminds me an old saying "barking dogs don't bite " I think her husband is a passive man and she controls him so she must be thinking that she can control everybody around her. Well I guess it's about time she learn her lesson. Good on your husband for not letting this go. She crossed the line in my opinion.
By the way, your lawyer should know this, you can take her to court for harassment. And as a proof you could show the court all your emails and text messages. Even the received calls from her when she called you in the middle of the night. You can also show them the term letter as a proof as well.