After her alleged messy breakup with Justin Bieber, Selena Gomez isn't getting mad, she's getting even, according to sources.

Gomez, 20, has already started laying down tracks for new music about their breakup, according to HollywoodLife.com.

“Justin was so mean to Selena that she can’t wait to spill all the s**t about him in her new songs,” HollywoodLife.com's source says. “All his flirting and all his…bulls**t are on the table. Her fans will be shocked about how much of a bada** she can be when she’s out for revenge.”