Rearranging the sequence of Events
Club Silencio is not a transition scene between the two main parts dream and reality. It is the 3rd. The final one.
The story starts when
Diane wakes up. Camilla comes around and tells her their affair's over, they
have a fight. When Diane realizes (after the dinner party) Camilla won't come
back to her, she hires a hatchetman to kill her. She's jealous, she's crazy, she
feels remorse, she ...
Then the Cowboy enters and says: it's time to wake up, baby (i.e. you have another chance, another try).
And we see her going down the escalator at the airport. Now she's Betty. She meets Rita. Betty suddenly remembers that she loved her. She loved Camilla when she was Diane. When they come home from Club Silencio, Betty disappears. (Rita whispers "Donde estas?" - "Where are you?") Rita opens the mysterious blue box. And then it's all ends.
IT'S OVER. THE DREAM IS OVER. Another chance, another try turned out to be a dream. And it ends. Silencio.