It’s bitch-fight time in Hollywood. Demi Moore has strayed from her longtime stylist, Rachel Zoe, in favor of Zoe’s former assistant, Brad Goreski, causing huge drama. A source told us, “Brad is dressing Demi for the Oscar parties, and he also dressed her at Sundance.” Moore was a longtime client of Zoe and appeared on her Bravo show. But she seems to have taken her allegiance elsewhere after Goreski broke with Zoe and set up on his own last October. Our source said, “Rachel is furious. Brad assisted her in styling Demi. Now she feels betrayed.” Reps for Zoe and Moore didn’t get back to us. Goreski said, “No comment.”