Although that sounds good, on a serious note I really going with option "a". Right now, it's unknown whether her email was a viable threat or it was a reaction to your email with a link to a mediator. Maybe she didn't like it that you were hijacking her agenda and it's a power struggle right now where she wants to take back control? Also, I believe the timeline was the OW's Mom was supposed to move in with her by now. However, I don't believe OM has moved in yet, has he? Right now it's only threats if that's the case. Your W has not learned yet what she's signing up for.
Ultimately, it you're decision and you're living the situation right now. If you are 300% sure you're done, then option "b"'s your choice.
I'm still praying for you. Especially for you to have the wisdom to make the right decision.
