The jabs at Taylor's then-boyfriend hit an especially sour note, as her relationship with the Scottish DJ (caught by RadarOnline.com
at a seedy massage parlor
) had already been difficult.
“Normally, Taylor wouldn’t care too much about backstage babble, but Carrie really rubs her the wrong way,” dished the confidante. “The two managed to keep their mutual distaste for one another under wraps, but Carrie had to do serious damage control after their hostility boiled over at the 2013 Grammys.”