Curry poisoner Lakhvir Singh was jailed for at least 23 years without showing a flicker of emotion for the lives she had ruined.
The married mother of three was branded a "cold and calculating" woman who had sought revenge.
Old Bailey Judge Paul Worsley sent her to prison for life and told her she would be approaching 70 before she could be considered for parole.
Singh, 45, of Southall, west London, was found guilty on Wednesday of murdering her lover, Lakhvinder "Lucky" Cheema, 39, when he decided to marry a younger woman.
She slipped into his Feltham home - used as a love nest during their 16-year secret affair - and sprinkled poison into curry in the fridge.
Later, Mr Cheema and his fiancee, Gurjeet Choongh, 21, ate the meal while discussing plans for their wedding due two weeks later on St Valentine's Day last year. Within hours, Mr Cheema died in agony and Miss Choongh was fighting for her life.
Miss Choongh survived and was in the public gallery to see Singh, whose husband is ill with cancer, led from the court.
Singh was also convicted of causing grievous bodily harm to Miss Choongh but cleared of attempted murder and administering poison to Mr Cheema in December 2008. She is thought to have brought deadly aconite from India in order to make Mr Cheema so ill that he returned to her.
Judge Worsley told Singh: "You were not just a spurned lover, you did not simply explode in anger at your rejection. You set about a cold and calculating revenge. You have shown no remorse whatsoever. Your actions came as close as may be to claiming the lives of two people on the verge of a new life together."
Earlier, Miss Choongh told the court in a victim impact statement: "I am still under a lot of stress. It preys on my mind all the time. The time I spent in hospital was a very difficult time for me. I did not speak English, my family were not with me to take care of me and I felt completely alone and isolated."
