Demi-monde

Paris society borrows fashions from the demi-monde, and the demi-monde borrows manners from the extravagant princesses, countesses, and viscountesses. All Parie has been stirred with the Sardanapalian entertainment, which a leader of the demi-monde gave on the eve of Lent to the best male society in the Empire. The ladies were all unquestionably from young [Alexandre] Dumas' panier à quinze sous; but their manners and their toilettes were, we are told, all that could be desired.

Source: wiktionary

This is the last straw. In your infatuation for this man—a man who is notorious for his excesses, a man your father would not have allowed to so much as mention your name—you have reflected the demi-monde rather than the circles in which you have presumably grown up.

Source: wiktionary