Do we exist?

15 year old spoiled girl Alixandra a.k.a Alix comes back from her every day midnight drive, when she comes back she sees a girl about her age in her bed, she runs to her parents when she realizes that they don't recognize her, she goes to the police who doesn't belive her either, until when she gets out of the police station she sees a guy about her age leaning on her car. And when they get closer to each other he tells her something. 'They didn't believe you either?'

What happened to them? Did they never exist? How are they gonna go to their old life, if they even had one.