A group of the Metropolitan Museum’s neighbors is mobilizing to oppose the museum’s expansion plans. Museum foes are circulating a letter: “If the Museum goes ahead, it will own our lives until at least 2015. We have a window of opportunity to act now, before the first jackhammer bursts or the first blast shakes. Can you imagine the negative impact on the value of your home if trying to sell during the 12-year assault? We could stop the whole magilla.” But now a group of opponents to the Met’s opponents has sprung up, charging self-interest…