So Maureen wants to have a marriage of convenience with Trip to retain her social position, offering an arrangement to both Trip and Serena. Letting Serena stay Trip's mistress, she explains, is "a time-honored political tradition. I'm Jackie, you're Marilyn."
It seems Maureen gets what she wants after Trip wrecks his car with Serena inside, but just to make sure she's done ample damage, she goes all the way to the city, to Rufus, with the letter. It was brought up that Lily may have cheated with Serena's dad, but it's still not clear, so now I'm annoyed. Two episodes is too long to go without know what's in the letter!