Timothy Brehmer was jailed for 10-and-a-half years after admitting the manslaughter of 41-year-old Claire Parry in Dorset on 9 May.
He had claimed she died accidentally during a “kerfuffle” in his car.
The Court of Appeal ruled that Brehmer’s sentence should be increased to 13-and-a-half years.
Brehmer, of Hordle, Hampshire, had pleaded guilty to manslaughter ahead of his trial at Salisbury Crown Court, where a jury cleared him of murder.
The Attorney General’s Office referred the case to the Court of Appeal under the unduly lenient sentence scheme.
The Lord Chief Justice Lord Burnett said that sentencing judge Mr Justice Jacobs “gave too little weight to the aggravating factors he had identified”.
He added that Mr Justice Jacobs had given too large a discount for Brehmer’s guilty plea as it did not “reduce the impact of the crime upon victims” or save witnesses from having to testify.
“The offender’s conduct and lies after the attack were reprehensible and calculated to deflect attention from what he had done,” Lord Burnett said.
Attorney General Michael Ellis QC, who welcomed the increase in sentence, said:
“Because of his actions, Claire Parry’s family have lost a wife and mother, and her community have lost a dedicated nurse.”
Mrs Parry’s husband, Andrew, previously said he was “incredibly disappointed” after Brehmer was cleared of murder and branded the former police officer a “well-practised liar”.
“He has shown himself – as the trial exposed – to be consistently dishonest, deceitful and devious,” he added.
The Court of Appeal rejected an attempt by Brehmer’s lawyers to have his jail term