Is Demi jealous that Brenda is dating her ex?

Not at all! Demi and Trace split last summer because of their four year age difference. "When someone is that much younger, you're looking for different things in relationships," Trace says. So it makes total sense that Trace would mesh with Brenda (who's only a year older than him). Even though Demi and Trace are still friends, Demi's moved on and she's way too busy with her career to care who Trace is seeing now.