Nothing. You handled the convo perfectly. The ball is still in her court, let her do all the work. Honestly I think she was threatening you with a L in the hopes that YOU would take control of mediation (IE, lesser of two evils). Based on all your posts I just can't imagine her actually doing any heavy lifting on this though.
JS, I was about to scroll down and type out a message almost verbatim to what AS said here. Good job on handling that call. Your W is stuck in the delusion of action. She continues to try to get you to take over the D by doing as little as possible herself. Not following up with mediation. Calling lawyers but not making appointments. This is all meant as a way to say "I'm done, so you should follow up on all of this for me." She was obviously looking for a reaction from you. More than likely the contacting lawyers was likely her trying to scare you into taking over and scheduling mediation.
As AS said, what we know of her history, this will likely go no where. Have you handled most of the logistics in your MR up to this point?
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018