Complex sentence: The entire experience is revealed to be a vision of the future as seen in the crystal ball of a Gypsy telling the fortune of someone with the same voice and name as Barney, who is apparently not the main character in his own fortune.
Split into simpler sentences: The entire experience is revealed to be a vision of the future as seen in the crystal ball of a Gypsy telling the fortune of someone with the same voice and name as Barney. It is of some note that Barney is apparently not the main character in his own fortune.