The American reality star, 30, was holding a live Q&A on Instagram when the former Girls Aloud singer went berserk.
Chad accused Sarah, 35, of being drunk and threatened to leave her.
He refused to end the live video call to tend to his other half who was in the bathroom.
“Sarah Harding is not helping herself”
She bombarded Chad with abuse calling him a “p***y” and then blasted him again when he defended her from fans who criticised her behaviour.
Sarah ranted: “Talking on phone slated by b***** a**** f****** take it up the a*** for ***.”
She then repeatedly used the offensive homophobic word “b***y”.
Shocked fans accused her of scuppering her bid to rebuild her image.
One said: “For someone trying to turn public opinion round & salvage a career #SarahHarding is not helping herself. Seriously get some help, woman #CBB.”
Another tweeted: “Vile homophobic slurs from your recent #CBB winner.”
The incident started when Sarah was in the bath, while Chad lay topless on a bed during the Q&A in a hotel room.
She shouted: “Chad! Come here!”
He responds: “I can’t come here at the moment, I’ve come here plenty of times.”
The American star is then heard defending Sarah as comments pop up on his live broadcast and turn abusive about the singer.
Sarah continues shouting: “Chad I need to have a wee,” while Chad warns: “There’s 400 people listening to you right now.”
Unashamed, Sarah’s language turns blue, telling Chad to “f*** off then” and demanding he turn his phone around so fans can see her. She also brands him a “p***y” while Chad then notes that members of the public listening to the argument are asking if Sarah is drunk.
Sarah continues: “I’ll get back in the tub, that’s better right, no t******.
“There’s no f******* nipples, there’s such a thing as censoring, check can anyone see anything, anyone see nipplage? Test it, can anyone see my t***?”
The pair were spotted leaving their London hotel yesterday.