Dunno what action I can suggest to you--it is a tough situation.
I don't know what to do, if the abuser lives, then what? If he dies, is there closure then? Or is she going to become totally dysregulated?
As for this question: I think she is going to find her own level of peace (or lack of it!) regarding her abuser. If he dies, she still has to find her own peace... . and now with some additional stress added to the mix. His death is another chance for her to address it, for better or for worse, or just avoid coping with it.
I hope she finds some healing.