Caitlyn had heard what the Doctor had said and nods. If it was as bad as the Doctor was making it sound, this would be hell. So she would make sure that Jack got better. "I'll play nurse, but I am rusty at it." She said for although some basic things had stuck with her she hasn't dared to go back to being a nurse for fear that he would find her. 
Rose softly places a hand on the Doctor's shoulder smiling. "I know you won't resort to killing him. Its what you do." She says lovingly. If he had a choice, he never resorted to violence or killing. After all why call himself a man who heals if he did resort to violence?