We've seen the aftermath of the incident - Marcie down amongst broken concrete and rebar and Sal having to be pulled off of Leyland. However, as of yet we can only infer the exact circumstances.
It's funny that Sal has a Secret Origin story so similar to many mainstream superheroes and costumed vigilantes: "Never again." Meanwhile, Amber/Amazi-Girl fits into a different trope, similar to some interpretations of Batman: "I must find a good outlet for my darkness."
Being a superhero story nerd, I can't help but be attracted to the idea of the two of them teaming up, at least for a little while, as a kind of team therapy.