Well, let's look at those things. Those details certainly fit your victim narrative, the story you like to tell yourself. But, there really is more than one side to these stories.
You seem to ASSume -- that her laughter was ABOUT YOU meant to hurt you and show contempt, you take it as an attack. Maybe it was.
But keep in mind that GF was not trying to hurt you when she and XH started the A, she was trying to address her own pain. I can't quite remember how the A was exposed, but I'm pretty sure that you did it in a manner intended to hurt her. That is, you WERE trying to hurt her. And, neither XH nor GF were particularly keen on giving up their families. Didn't GF try to reconcile (briefly)? Remember XH's crazy idea about you three living together or something? You made things happen that caused them pain and embarrassment and tore apart their families before they were ready. Not saying you did anything wrong, merely stating fact. So, maybe her laughter was a form of hitting you back, a form of aggression. But, certainly you can understand striking out at someone who harms you? So, perhaps it was a hostile act by a desperate woman in pain striking out at the wrong targets.
But, really, I think it was probably uncontrollable nervous laughter due to her shame and embarrassment combined with the high stress of the situation.
Or maybe it was due to fear. You really don't know.
But, I personally doubt it was the laugh of an evil monster who intended to injure you. She was your friend, she cares for your children, I think you probably would have noticed before the A if she were evil incarnate.
Try reading here, especially B. Aggression, C. Fear, and D. Social Anxiety. I'd put money on her laugh falling under C or D rather than B.
Of course, that doesn't fit the victim narrative so nicely.
