Harvey, who has just turned nine, is autistic and has Prader-Willi syndrome, a rare genetic condition affecting the area of the brain that controls appetite.
Katie, who had Harvey with footballer Dwight Yorke, writes:
'So you will understand the extent of my shock and anger when I learned that Frankie Boyle, the comedian - though he barely deserves the title - had singled my son out to be the butt of a vile 'joke'. To convey the full impact of what Boyle said on his Channel 4 'comedy' show last December, I must, I'm afraid, repeat his offensive remarks in full. To begin with, he said my ex-husband, Peter Andre, and I had been fighting over custody of Harvey. 'Eventually one of them will lose and have to keep him,' Boyle said.'
'Then Boyle made a remark so offensive it has no place in civilised society. Referring to my second marriage, to Alex Reid - we have since separated - he said: 'I have a theory about the reason Jordan married a cage-fighter - she needed a man strong enough to stop Harvey from f***ing her.''
Katie goes on to write that neither Boyle or Channel Four have apologised for the outrageous comments, and have ignored her requests for one.
She added: 'I can't overstate the outrage and revulsion I felt when I heard this attack on my vulnerable, disabled son. I am used to defending myself against insults and, at times, justified criticism.'
Katie will front a programme, airing this evening, about the realities of life with a disabled child, Katie: Standing Up For Harvey, Sky Living, 9pm.
Regardless of your views on Jordan/Katie, there's no way anyone should be allowed to joke about her disabled son like that, is there?