I don't get Helen's behaviour

Ok, so she got agoraphobia from a traumatising event. Sure. And she freaks out from that email with the video of the next victim, perfectly understandable.

But why doesn't she so much as bat an eyebrow on seeing that red dress laid out on her bed, when she thought she was alone, telling her quite clearly that someone (obviously the serial killer) had been INSIDE her apartment? Andy wouldn't have done anything like that. She doesn't call the cops then, and when she finally does call the cops, she doesn't even mention this. In fact, when she freaks out after the email, the detectives offer her police protection but she refuses adamantly. She even says "this is the only space that I have in the world". She's hysterical that the killer could sneak into her computer, but doesn't care at all that he can sneak into her apartment whenever he feels like it - that in fact, he already has, and she knows it. So what gives?