It gets tricky, because confidentiality can be trumped by safety concerns. I've been in similar situations and would not have done this. Instead a T would have the client contract for safety and come up with a plan before leaving the office. If that's not an option for some reason, however, then the next step could be to contact someone. So, if this T felt there was significant risk then they acted appropriately, at least as far as ethics are concerned. I think the OP is justified in being angry and should say something if she wants to. I just doubt anything will happen to this T beyond a conversation about what to do next time.