I'm with MrFisher... you lose nothing by trying this approach. You can say you might be able to help her in the future but your accounts are being monitored right now. I know mine were when I got Divorced. Then ignore her. Do not reply to emails or texts. I wouldn't change phones, emails... just stop using them & accumulate the threats & evidence. Switch over to new phone & email for your active use. Drop off the grid as much possible.
With divorce pending, your atty will still need to know so he's not blindsided. If they come back then get the cease & desist letter. Hopefully by then there will be enough evidence to charge her with blackmail.