Delacey, Courtesy: Aysia Marotta. Even if you haven’t listened to any of Delacey‘s first three singles yet, you’ve probably heard one of her songs. The singer-songwriter, whose real name is Brittany Amaradio, wrote “New York City” on The Chainsmokers’ 2015 album, Bouquet, as well as Halsey’s “Without Me,” which reached No. 1 on the…