Steven Jackson, 40, battered and stabbed former partner Kimberley MacKenzie at a flat in Montrose before cutting up her body in a bathtub.
Co-accused Michelle Higgins, 29, was jailed for eight years for helping to dispose of Ms MacKenzie's remains.
The couple were convicted following a five-week trial.
A murder charge against Higgins was found not proven by a jury at the High Court in Glasgow.
Judge Lady Rae told Jackson and Higgins: "The behaviour of both of you was despicable and callous.
"The killing appears to have been a wholly motiveless and brutal murder of a defenceless woman.
"What you both did to the body of the deceased shows a level of depravity, thankfully, not often seen in these courts."
The trial heard that Ms MacKenzie, 37, sustained at least 11 blows to the head and was stabbed more than 40 times.
During the trial, each of the accused blamed the other for murdering Ms MacKenzie.
Higgins claimed that she was so terrified of Jackson that she helped him dispose of Ms MacKenzie's body after he had killed her.
The trial was told Jackson targeted Kimberley MacKenzie in a frenzied attack with two knives, a hammer and a large paint scraper on 27 October last year.
The following day he chopped up her body in the bath and, with the assistance of girlfriend Higgins, dumped the body parts in four bins in Montrose.
The pair were captured on CCTV walking through the streets of Montrose carrying a child's rucksack and a green suitcase containing more body parts including Ms MacKenzie's head.
The trial heard that Jackson confessed to his ex-wife Barbara Whyte that he had killed Ms MacKenzie and chopped up her body.
A man has been jailed for a minimum of 26 years for murdering and dismembering a mother of three and and hiding her body parts in bins.