You can do this. You are about to round a corner of regaining your life back. That's going to help. You are going to see them at one point, dear Savvy, but later, rather than sooner would be better so avoid the route in which you could see. Think Clara in Texas-the dentist who ran over her husband. You don't want to be tempted.
Hopefully the STBX will be decent about this one thing for a bit anyway. Just be careful. If they become revengeful, they will go for it. By that I mean, probably wise to not bring up again. Don't remind him it's a weak spot because they ARE liars, asshats etc.
Just determine they have been given too much space in your life as it is. They have a plague. Sick people. Avoid.
That sucks big time. I'm sorry Savvy.
If you see them together, RUN up to her, extend your hand & say as loud as possible "DARLING! I've
been LOOKING for you! I want to extend my hand to you. Help you up out of that gutter you fell in."
Hugs. Prayers for you too.