"This monster of narcissism values only himself and his pale reflections. The disabled, minorities, transgender people, the poor, women (unless related to him by ties of blood, and therefore his creations) are treated with contempt, because they do not resemble Trump.
"My mother used a wheelchair. I witnessed people uncomfortable around her disability, but if they had a shred of decency they got over it. So yes, that clip of Trump looking deliberately over a disabled child's head, ignoring his outstretched hand, has touched me on the raw.
"That man occupies the most powerful office in the free world and his daily outrages against civilised norms are having a corrosive effect. How stunning, and how horrible, that Trump cannot bring himself to shake the hand of a small boy who only wanted to touch the president."
There was just one problem with Ms Rowling's heartfelt rant - Mr Trump hadn't ignored the boy at all.
Ms Rowling seems to have based her tweetstorm on an edited clip that popped up on social media, appearing to show Mr Trump snubbing the boy, whose name is Monty. But that clip has since been deleted, and an unedited version released by the White House clearly shows the president greeting him (watch video above).
Despite that fact, Ms Rowling has so far refused to correct the record, earning her the ire of her fellow Twitter users - foremost among them British morning TV host Piers Morgan.
"JK Rowling's been back on Twitter but neither deleted, nor apologised for, this disgraceful lie. Her Trump-loathing knows no honesty," Mr Morgan said.
Meanwhile, Monty's mother posted on Facebook in an attempt to get Ms Rowling to recognise the truth.
"If someone can get a message to JK Rowling: Trump didn't snub my son and Monty wasn't even trying to shake his hand," Majorie Kelly Weer said on Facebook.
"He's three and hand shaking is not his thing. He was showing off his newly acquired secret service patch."
Ms Rowling's behaviour contrasted poorly with that of Chelsea Clinton, who also accused Mr Trump of snubbing Monty and also suffered a backlash - before realising her mistake and correcting it.
