Ramona Singerwas the ultimate party crasher when she unexpectedly showed up at the Real Housewives Ultimate Girls Trip: RHONY Legacy premiere, months after she was canceled for allegedly using the n-word, RadarOnline.com has learned. Sources shared she was “not invited” to the event, which took place at GH on the Park in New York on Tuesday evening. The invitation to the party promoted appearances byRHONY: Legacy stars Luann de Lesseps, Sonja Morgan, Dorinda Medley, Kelly Bensimon, and Kristen Taekman — but Singer was reportedly left off the invite, with Page Six reporting she was planning to …