Donald Payne, 64, carried out the 'dreadful, appalling' attack on Simone Ambler, 49, following an argument at their Dinmore Avenue home on March 29, last year.
After stabbing the mum of two 70 times, he called the police and said: "We had an argument about drugs. She wants to go out and I don't want her to go out. I stabbed, I've stabbed her."
He added: "I've been arguing with her. I don't want to be with her. She's been getting on my nerves."
Police attended the scene shortly after 9.20pm, where they found Ms Ambler face-down on the floor and Payne sitting in a chair nearby, watching television.
Mr Cummings, prosecuting, said: "The victim had received multiple wounds all over her body. The effect of that was that sadly, despite the presence of a number of paramedics, a decision was taken fairly soon that Ms Ambler had died."
A post-mortem identified 70 knife injuries from a 13cm pronged blade found at the crime scene.
Mr Cummings said: "(She had) three wounds to the head. 11 wounds to the neck. Particular injuries to the neck which appear very serious are a 5.5cm wound to the left side of the neck, and another penetrating 11cm. Another wound of 3cm and a further two of 2cm, cutting the artery."
A further 18 injuries were found to the chest, 11 to the abdomen, eight to the left arm, nine to the right arm, eight to the left leg, and six to the right.
She had also suffered a number of rib fractures which would have required considerable force.
Payne was charged with murder and pleaded guilty to the lesser charge of manslaughter in November last year.
At his sentencing at Preston Crown Court today, Judge Simon Medland heard that Payne had been suffering from an undiagnosed psychotic illness at the time of the attack, which had been worsened by his long-term use of alcohol, heroin, crack cocaine and spice.
His daughter Emily Payne said: "My dad did not trust authority figures. He was adamant they were after him and he mentioned that Simone was putting stuff into his tea and indicated that she was working for them."
Another witness said Payne had said Mr Ambler was 'making him go mental' and the he thought she had been drugging him.
Ms Taylor, defending, argued that Payne's condition had significantly affected his ability to act rationally.
"Often when this level of violence is used, it shows an utter loss of self control, which is what psychiatrists say has happened in this case," she said.
She added: "He didn't know she had two daughters because she was estranged from them. When he learned of the existence of her daughters, he was visibly saddened. He has expressed remorse. He's incredibly sorry for what he did. He was shocked to find out the number of wounds he inflicted."
But Judge Medland ruled that Payne posed a serious risk to the public, particularly women.
He had 49 previous convictions, including an eight year prison sentence for grievous bodily harm in 1991. In March 2012, he received an eight week sentence for waving a knife at his ex-wife and threatening to kill her.
The judge said: "The manner of this killing was a dreadfully appalling attack with a knife. There are 70-odd stab wounds on the victim and they would have required considerable force to inflict. This is not the first time you have attacked another person, in particular another female partner.
"You are 64 and you have many offences against your name committed over many years - but I balance this against the dreadful nature of your upbringing.
"You have continued to use drugs over many years, including spice... the outcome is you carried out a dreadful attack on your female partner.
"This was during a psychotic episode, but a psychotic episode which was, in part, caused by your voluntary use of substances which had greatly unbalanced your mental stability.
"Considering the previous convictions... the defendant has evidenced himself as capable of serious violent offences and under these circumstances its my view that he poses a serious risk of harm to known adults."
Payne was given a life sentence reduced to 18 years due to his guilty plea. He must serve a minimum of 12 years, minus the 435 days he has already spent in custody, before he is considered for release.