Former police officer Timothy Brehmer has had his sentence for the manslaughter of long-term lover Claire Parry increased to 13-and-a-half years by the Court of Appeal.
After the ruling, acting Attorney General Michael Ellis QC, said: "Because of his actions, Claire Parry's family have lost a wife and mother, and her community have lost a dedicated nurse.
"I greatly welcome the decision by the Court of Appeal today to increase Brehmer's sentence."
Brehmer, 41, a former Dorset Police constable, strangled Mrs Parry, a mother-of-two, after she sent a text message from his phone to his wife, saying: "I am cheating on you."
Mrs Parry died the following day and her cause of death was a brain injury caused by compression of the neck, a post-mortem found.
The 41-year-old married nurse died, he said, during a "kerfuffle" in his car in the car park of the Horns Inn in West Parley, Dorset, last May.
Brehmer, of Hordle, Hampshire, claimed she accidentally suffered the fatal injury while he was trying to push her out of his Citroen so he could drive away.
He said he then left the car without realising Mrs Parry was "poorly" and he didn't intend to hurt her "in any shape or form".
Rather, he claimed, he was planning to go and kill himself because of the consequences to his family of their affair being revealed.
The pair had been in a relationship for more than 10 years, the court at the trial heard.
Described in court as a "womaniser," the married man was cleared of murder by a jury at Salisbury Crown Court in October.
But he was jailed for 10-and-a-half-years for manslaughter, which he had previously admitted.
Following a referral by the Attorney General's Office (AGO) under the unduly lenient sentence scheme, the Court of Appeal increased his sentence by three years in a ruling on Friday.
The Lord Chief Justice Lord Burnett said that the sentencing judge, Mr Justice Jacobs, "gave too little weight to the aggravating factors he had identified".
Lord Burnett said: "We quash the sentence of 10 and a half years imprisonment and substitute a sentence of 13 and a half years imprisonment."
The Court of Appeal also rejected a bid by Brehmer to have his sentence reduced.