Wow. She sounds like a hot mess. On the one hand, i would not mind a message like that. I feel like it would give me some validity. On the other hand, when your that far out and healed i could see it feeling like rubbing an old wound. I think jobs post about her using you as the common enemy makes a lot of sense. Or perhaps, shes seeking validation as well. She didnt actually apologize or refer to her role in it though, so i doubt its a true remorse. Maybe she just wants proof that he really is bad.
I once had a cheating ex's other woman call me maybe 5 or 6 years later. (Not my ex husband but my 1st boyfriend) i was aquaintances with her, and she actually asked me why i never warned or or told her how bad he was. (He was very abusive) . She went out him knowing we were dating!!! Or that we were on fringe of breaking up. He only knew her because of me. By that time i was competely indifferent, so it left me amused at most. Amd surprised that she had wasted that many years of her life with him, and relieved that it wasnt me. And he was only a boyfriend, not a husband or father of my child.
Anyway, my hatred for walkaways makes me love hearing these types of stories and i have to confess, its a fantasy of mine to get the choice of how to adress something like this. So im living a bit vicariously through you. Yes, i know ow its better to just be indifferent.