Emmerson Mnangagwa, who had served as vice president since 2014 and who was exiled alongside Mr Mugabe during the 1970s war against white minority rule, was fired on Monday for “disloyalty, disrespect, deceit and being unreliable,” the country’s information ministry said in statement.
Mr Mnangagwa, 75, often referred to by his war-time name, Ngwenya, (crocodile) had long been tipped to succeed Mr Mugabe, 93, when he died or retired.
Mrs Mugabe publicly mocked him when he was in the audience at a public rally on Saturday.
The following day, she told thousands of Apostolic Church members that Mr Mnangagwa tried to overthrow her husband from independence onwards.
“In 1980 this person called Mnangagwa wanted to stage a coup. He wanted to wrestle power from the president. He was conspiring with whites. That man is a ravisher,” she said.
The comments provoked outrage from supporters of Mr Mnangagwa, who was jailed for fighting against white minority rule in the 1960s.
He was tortured in detention in Rhodesia and avoided the death penalty because the judge believed he was under 21 when he was sentenced, spent ten years in prison and on release qualified as a lawyer after studying at the University of Zambia and the University of London.
After Zimbabwean independence in 1980 he acted as Mr Mugabe’s hatchet man against internal opposition, and has been accused of orchestrating crackdowns which saw thousands killed.
In recent years he has emerged as Mr Mugabe’s heir apparent and the leader of one of two powerful factions vying for influence within the ruling Zanu PF party.
The “Lacoste” group, named for the sportswear brand’s crocodile logo and Mr Mnangagwa’s war time nickname, has been locked in an increasingly bitter succession struggle with the so-called G40 group, centred around Mrs Mugabe.
Mrs Mugabe said at the weekend she wanted to be a vice president and expects to be appointed to the post at the ruling Zanu PF’s congress next month.
“I say to Mr Mugabe you should … leave me to take over your post,” she said in her address to church followers.
The power struggle has raised fears of a political backlash and possible violence.
Mr Mnangagwa enjoys the backing of senior members of the Zimbabwe National Army, while the police support the Mugabe clan. Mr Mugabe previously announced that he might retire senior military leaders.
Others speculated that the ousted vice president may seek an alliance with Zimbabwe’s marginalized opposition.
Evan Tigere, 64, a veteran of the war against white rule in Rhodesia and now a street vendor in Harare’s streets, said: “This time Mugabe has pressed the wrong button. We now need to gather everyone in Zimbabwe to fight in the same corner to remove these idiots.
“How can we be run by husband and wife? Tell me which country has a husband and wife being president and vice at the same time?”
A civil servant working as a clerk within one of Harare’s main government buildings said she was shocked at the news. Chinopiwa Murefu, 36, said Mr Mnangagwa’s departure from Zanu PF presented an opportunity for the opposition Movement for Democratic Change, MDC to create an alliance with him at next year’s elections.
“We could form a formidable party to save this country,” she said.
“The vice president has consistently and persistently exhibited the traits of disloyalty, disrespect, deceitfulness and unreliability.”