‘Grey’s Anatomy’ fan thinks she’s on the show after dental surgery

“I need to go to Grey Sloan Memorial!” A heavily medicated woman believed she was the main character on ABC’s “Grey’s Anatomy” after getting her wisdom teeth removed. In the delirious video, accountant Tisha Heffron, 24, from Watertown, New York — not Seattle, Washington — says, “I want to marry Derek Shepherd” and “You gotta…