I'm going to go ahead and nominate Mariah Carey for not only "Most Petty" but also "Best Get Back" for 2017.
As the story goes, back in October, Mariah and her billionaire fiance' James Packard called off their wedding. There were some disagreements on who should give what jewelry and gifts back to the other person, etc. One of the victims of this split was the custom Valentino wedding gown which cost (someone) $250,000!
Mariah comes out with a very obvious heartbreak/break-up song called "I Don't" and not only films the video at the Calabasas mansion the former couple once shared, but burns the quarter million dollar wedding dress for a grand finale'.