Madame du Barry's behavior is natural: she was jealous of the Dauphine. Marie was witty, young, beautiful and had an excellent taste in fashion; Which represented a menace for Madame.
I wonder who exactly that 'infamous party' was? Who were the friends of Madame du Barry at court?
Quite interesting, haven't hear much about her in particular, she is one of the characters I have done in my 18th century collection!