I think she was always depressed
Despite the fake persona of happiness this woman has been sinking into to the pit of sadness for years. Let's start off with this first, despite her attempts after ''Precious'' came out to claim her childhood was 'nothing like that' we know that's a lie (she fessed up in her book).
She was bullied by her family and peers for her weight and looks since childhood. Had the darkest skin ton, the worst facial features and was 400 pounds (at least). After ''Precious'' she got bullied in the media and gained more weight. Never got cast in anything but small parts. She got diabetes and then had weight loss surgery (to attempt to save her life) but appears to have gained most of it back.
She's definitely f***** depressed.