S.S.
Talk to a lawyer about a restraining order - verbal harassment, slander, libel, or threatening your job, safety, or child - all of those are considered violence too. TRO's are common in divorce cases for those reasons.
In some cases (when they cause economic or physical hardship), you can sue her for it.
To me, the best way of dealing with her would be to change your number (unlisted), return all mail as "moved, no forwarding address", and change your email server... or notify hers of the harassing emails, and they'll terminate her account as a violation of TOS.. or both.
Your husband needs to cut the strings and stop looking for validation, too. It is my totally unprofessional opinion that he's still trying to have a relationship with her - because even psychos don't typically pursue over long distances without a little encouragement. (I was raised by my father's parents, too - and now both of my birth parents are trying to get in on the game).
S.