You attempted to fight Doopliss, the duplighost, and it seemed like you won! Well... No, you actually lost and got turned into a shadow, and if you don't actually defeat him soon you'll permanently dissapear! All your partners think you're a fake and Doopliss is real, fortunately you did meet Vivian who actually decided to help you get your body back, all you heard was Doopliss say "Yuk yuk yuk yuk," as in laughing.