Cat Marnell, the drug-addicted beauty columnist for Jane Pratt’s Web site xoJane.com, has parted ways from the site after refusing to get clean. Marnell chronicled her drug use on xoJane.com, and was profiled by New York magazine in April, the day before she entered rehab, as ordered by xoJane.com publisher Say Media. But sources say Marnell never stayed clean, with one suspecting she even worked high. “I’m always on drugs,” she wrote to us in an unapologetic e-mail. “Look, I couldn’t spend another summer meeting deadlines behind a computer at night when I could be on the rooftop of Le Bain looking for shooting stars and smoking angel dust with my friends and writing a book, which is what I’m doing next.” Marnell, formerly a beauty editor at Lucky, admitted she’s not fit for the 9-to-5. “Drug addicts undeniably bring editorial black magic to the table like nobody else, but obviously we make the worst staffers,” she wrote us. “We can fake it [for a time] . . . before we turn into coddled emotional vampire nightmares.”