Complex sentence: Diana is stuck in New York being one of the only two people that knows that her sisters death is a hoax, the other person, Penelope Hayes, decides that she would like to marry the famous and rich Henry Schoonmaker Jr., Elizabeths ex-fiance.
Split into simpler sentences: Diana is stuck in New York, being one of the only two people that knows that her sisters death is a hoax. The other person, Penelope Hayes, decides that she would like to marry the rich and famous Henry Schoonmaker Jr., Elizabeths ex-fiance.