After Cassandra Peterson called Ariana Grande her worst celebrity encounter, the singer addressed meeting her 'around 7 years ago,' writing in an Instagram comment on Monday, Oct. 21 that she was 'so disheartened to see

Actress Cassandra Peterson, who's best known for her Mistress of the Dark alter-ego, said Ariana Grande had requested tickets for herself and family members to one of her stage shows. She told a panel that she'd posed for photos and signed autographs for "all her friends and relatives" but that Ariana had refused to pose for a picture in return and left before the performance.