Jason Carr strangled Sarah Fuller in April, having started a relationship after moving into her Exeter home as a lodger six months earlier.
Exeter Crown Court heard how Carr phoned police after initially fleeing the scene and said "basically, I have killed my girlfriend". The judge said the mother of two had suffered "a terrible death". The pair had been arguing during dinner on 16 April, with friends saying they had been "sniping" at each other.
At on 17 April he called police from a mile and a half away and confessed to the killing. He told officers: "Basically, I have killed my girlfriend.
We have been arguing for months and months and months and tonight I strangled her. She took Carr back a few weeks before she was killed. Judge Peter Carr told him: "You strangled her with a tight grip for around 30 seconds.
She last thing she would have seen was the face of the man who was killing her and taking her away from her children. She struggled but you were too strong and too determined to kill her.
I have no doubt you intended to kill her. He will serve a minimum of 14 years and two months in jail.