The story in question is probably best encapsulated by the pornstar's guest article on Jezebel....
...but if you don't feel like reading that then here's a summary:
BBW pornstar "Juicy Jackie" recently saw herself in a newspaper ad for a dating site called Ashley Madison. The photo was part of a shoot she had done early in her career, and she had no idea that the photographer had sold those pictures for ads and such. That didn't really piss her off much, mainly because she obviously signed a release but also because she was too busy raging against the advertisement itself. The photo is over her in a 'sexy' pose, but with the caption "DID YOUR WIFE SCARE YOU LAST NIGHT?", with the obvious implication that fat women are no only unattractive but frightening enough to prompt their husbands to sign up for sleazy dating sites with the expressed intention to cheat.
The blog post talks a lot about the culture of body-shaming and how unhealthy it is for our society to shame fat women out of being proud of their bodies, and about how shitty the concept of a site like Ashley Madison is. In response, the site issued a statement accusing Juicy Jackie of using the controversy solely for free press, saying "The best thing that could've happened to this woman is that we used her in our ad."