What is Lady Portarles wise advice?

From the text:

“Bless the woman!” ejaculated Lady Portarles, “did ever anyone see such perversity? My Lord Grenville, you have the gift of gab, will you please explain to Madame la Comtesse that she is acting like a fool. In your position here in England, Madame,” she added, turning a wrathful and resolute face towards the Comtesse, “you cannot afford to put on the hoity-toity airs you French aristocrats are so fond of. Lady Blakeney may or may not be in sympathy with those Ruffians in France; she may or may not have had anything to do with the arrest and condemnation of St. Cyr, or whatever the man’s name is, but she is the leader of fashion in this country; Sir Percy Blakeney has more money than any half-dozen other men put together, he is hand and glove with royalty, and your trying to snub Lady Blakeney will not harm her, but will make you look a fool. Isn’t that so, my Lord?”