Demi Lovato just went nuclear on Instagram ... for allowing a disgusting ad fat-shaming women to end up on her feed.
The singer blasted the social media platform Friday with several posts ... going off after a sponsored ad for a mobile game appeared. Demi wasn't having it ... straight-up asking how the mobile app "Game of Sultans" can get away with fat shaming.
Ad - Character - Left
You can see in the ad a character on the left labeled as "obese" and...