Justin Bieber who? Selena Gomez is single and ready to mingle… and so that’s exactly what she’s doing!Ever since splitting with Justin, 18, over New Year’s, sources tell omg! the "Love You Like a Love Song” singer is focused on two things: friends and music.Gomez, 20, was spotted at a slew of Golden Globes parties where sources tell us she "looked like she was having a lot of fun.”On Sunday night, Gomez had a few famous main partners in crime: Vanessa Hudgens, Ashley Tisdale, Sarah Hyland, and Josh Hutcherson. The foursome party hopped from the InStyle/Warner Bros. soiree to the Weinstein bash before landing at the end of the night at CAA’s private party at the Sunset Tower Hotel."If she was upset about [her breakup] she didn’t show it,” an onlooker at the hotel tells omg!. "She was smiling, dancing with her girls and spent time talking with Josh.”So could Selena be sparking up a romance with "The Hunger Games” star? A source close to Gomez tells us "definitely not.”"They have a lot of mutual friends — their night together was totally innocent,” says the source who adds that Gomez has been leaning on friends for support post-split. OMG