At this point, there isn't a whole lot you CAN do - she sounds like a bitter woman making bad parenting choices - hopefully when she cares for her daughter, she is at least a good mother but who knows if someone is willing to act like this anyway - it sounds like a very hard situation - I'm sorry you have to deal with it at al!!
I don't think your safety is in danger unless you think she is mental enough to shoot him or something. She sounds like she has serious anger issues and I understand why he split from her. :( And that poor baby having to be around that is awful. Is there anyone around them you can have check up on them? And keep an eye out for the safety of the child? Or due to the assault could your attorney have CPS check in on her and her behavior? I would check into it. As far as this week goes, if she doesn't respond send the cops by and say that you are worried about your step-daughter since you haven't heard from the custodial mom and you have made several attempts to contact her. Good luck!