PENNSYLVANIA, US:  Taylor Swift is planning to get revenge on Justin Bieber. Bieber disses ex-girlfriend Selena Goemz’s BFF Taylor on his new track All Bad - so Taylor will fire back in her and Selena’s defense. “She has heard the song, and she is definitely going to respond at some point,” a source says. “She has the mentality now that payback is a b**ch. A song about him has no timetable but it’s inevitable.” The singer who’s dabbled at acting in TV shows like CSI, New Girl and the movie Valentine’s Day - is getting ready to sink her teeth into beefier starring roles in movies.–SS