That was one of the more just flat out mean things WWE did and I feel bad for her. For those that don't know here's some cliffs -
In 2007, Mickie left Kenny from the Spirit Squad and started seeing Cena(who was still married). Cena had a reputation of sleeping with all the divas at the time. In 2009 he called it off and Mickie had a public meltdown backstage and was moved from Raw to SD.
Almost as soon as she got to SD she was given the Piggy James angle which consisted of LayCool basically calling her a pig every week because of her weight. For reference, this is what Mickie James looked like in 2009 -
She lost the feud, got injured for a month, came back, lost a couple more matches and was fired.