Obsessively jealous Phillip Manning, 42, waited in jail with "extreme bitterness in his heart and, undoubtedly, murder on his mind", Gerard Elias QC, prosecuting, told Cardiff Crown Court.
Manning, of Abertillery, Gwent, was released on licence last October on condition that he did not see Margaret Whitcombe, a mother-of-three and his wife for 20 years.
But he obtained a sawn-off shotgun and knife and ambushed her in the garden as she came home late last Christmas Eve with her boyfriend, Neil Jones.
After attacking Mr Jones with the knife, Manning fired twice at point- blank range at his ex-wife, fatally wounding her.
Following the killing, the former lorry driver became a fugitive for a month until he was arrested in London by police after he strapped a home-made nail-bomb to himself.
Mr Elias told the court: "Manning had an obsession with his former wife. If he couldn't have her, no one else would. He frequently expressed these sentiments to others."
Manning was released on parole after being given a four-and-a-half-year sentence for the attempted murder of his wife in 1992 when he repeatedly stabbed her and tried to strangle her. Throughout the attack, he was shouting: "You are going to die."
Mr Elias said when Manning was released on parole he returned to the area and asked an acquaintance to get a gun for him, saying he wanted to "do her".
His friend did nothing, but Manning managed to obtain a shortened shotgun.
Mrs Whitcombe, 42, was shot after Mr Jones had been beaten to the ground and hacked with a 12-inch butcher's knife which left him needing plastic surgery and a plate in his skull.
Her youngest son Daniel, 11, woken by the shots, ran downstairs and saw his father, Manning, in the garden, the court heard. Mrs Whitcombe's other son Christopher, 20, arrived home at that moment.
After threatening the rest of the family, Manning fled. He was arrested in the City of London by police who found the nail-bomb strapped to his waist.
Sentencing Manning to two terms of life imprisonment to run concurrently, for the murder of Mrs Whitcombe and the wounding of Mr Jones, Mr Justice Jowitt said he should not be considered for release while there was any risk of him becoming involved in an emotional relationship.
Outside court, Detective Superintendent Ian Johnston, of Gwent CID, said: "Fortunately, the rules on releasing violent prisoners have been changed and the police and victims have to be consulted before such a move is made.
"Manning was undoubtedly a very dangerous man."Reuse content