Once you file charges against him this becomes witness tampering and intimidation, get those charges filed, that will shut them up.
Ignore them until the charges are filed, block numbers, change your phone number, get a new email, whatever you have to do.
I am sorry you are going through this, but you really need to go no contact with them.
If you want to talk, vent, whatever, just let me know, I will be glad to listen.
Big hugs,
Bill