what’s the name of this horror movie?

In the movie a bunch of teenagers sneak out of their homes to go to the theater to see a horror movie, a friend of theirs works at the theater and lets them in to see the movie, after the movie has played for a little bit something goes wrong with the soda machine so the guy goes into the basement of the theater to switch it and the killer from the movie appears right behind him and kills him, and one by one the number of teenagers starts to go down, they even end up in the movie, at the end of the movie the last teenager is a girl, she hands a boy who had followed them to the theater a necklace and then tosses him out of the movie before it ends, but before all of this happens the movie begins with a guy in some kind of hospital who thinks or believes that he’s the killer from the movie then it cuts to a different part of the movie and the next time they show the hospital they show it with blood everywhere and nobody alive, as the kid walks out of the theater cops arrive and then the credits start? I saw this movie on Netflix a few years ago and ever since I watched it that one time I’ve never been able to remember the name of it much less find it since, if you know the name of this movie please tell me because I would love to see it again if not buy it on DVD.