Lucas Bigley, 19, stabbed Matthew Wilson to death in Sheffield on 28 May in a "violent and brutal attack".
Hull Crown Court heard the two men had fallen out after Mr Wilson, also 19, began a relationship with Bigley's mother.
Bigley, of Wadsley Lane, Sheffield, was told he must serve at least 22 years in jail.
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Hull Crown Court heard Bigley was still wearing his heavily blood-soaked clothing and attempting to wash the blood from his hands when was arrested in the early hours of 28 May.
Det Ch Insp Craig Jackson said: "This was a violent and brutal attack on Matthew, a young man whom Bigley once considered his friend.
"The court heard how both he and the victim knew each other for many years, but their friendship broke down after Matthew began a romantic relationship with Bigley's mother.
"His anger and frustration came to the fore in the early hours of that morning in May and a young man who had everything to live for has now tragically lost his life."
Mr Wilson's family said in a statement they were "satisfied" with the jury's verdict.
However, they added: "While we regard the sentence Bigley has been given as fair, no sentence will ever bring Matt back to us.
"We too have been handed a life sentence."
A man has been jailed for life for murdering a former friend who was having a relationship with his mother.