Context: at a birthday party my 11-years old sister watched Annabelle and Annabelle 2. She told us later that even though she was frightned the whole time, she didn't want to stop watching, mainly for a matter of pride. She explained that even though the films were being watched mainly by girls of 14-15 years old, there were a couple of younger ones (around 7/8 years old) watching, too. These younger girls were not very scared of the movie because they could not read the subtitles and so didn't really know what was happening; so my sister didn't want to appear to be more scared than everyone else.
Since then she has been waking up every night in terror. She wakes up, super scared, and goes to my parents bed; that's the only way she'll go back to sleep. Getting her to fall asleep is also very very hard; she says she can't stop thinking about the doll. She knows that the doll isn't real, that any of it isn't real; she says so herself. But still, she says that whenever she closes her eyes she just keeps imagining the doll behind her, or appearing by her side.
I have no idea what to do to comfort her, or make her fear go away. Again, it's not a matter of knowing the doll is not real; she keeps emphasising to us that she knows it isn't. But still, it seems that she is not being able to deal with her fear or her thoughts.
What are some strategies to make her feel safe and help her deal with her fear?