He stabbed her 49 times in the head, neck, body and arm
Salum, who had a history of violence against an ex-wife, was living in Britain on a six-month visa having wedded Ms Mtumwa in east Africa.
The night before the murder on 20 March, the Tanzanian had become jealous because his wife had gone out with female friends, the Old Bailey heard.
Just before 7am, he fell into a "violent rage" and attempted to strangle her at their home in Haringey, north London.
He broke off and went into the kitchen to get a knife which he used to stab her 49 times in the head, neck, body and arms, the court was told.
Ms Mtumwa's 12-year-old son had screamed at him to stop before alerting police. When he was arrested, Salum claimed he had acted in self defence.
Initially, he denied murder but changed his plea at the 11th hour at the Old Bailey.
The court heard Salum had been "extremely violent" towards his ex-wife in the past and had "lied through his teeth" when he claimed to police he had been defending himself at all times.
The court heard the victim's parents had been left devastated by her death.