Christopher Griffiths, 30, Daniel Roberts, 20, and Awaz Jamshaid, 19, received a total of 61 years in jail for killing 20-year-old Malaciah Thomas.
Cardiff Crown Court heard Mr Thomas had been in a relationship with girlfriend Naomi Davies at the same time she was also seeing drug dealer Roberts, who fell into a "jealous rage" over her "two-timing".
Roberts and his friend Griffiths, who had appeared in Sky documentary School Of Hard Knocks where young men were given rugby training in order to turn their lives around, repeatedly stabbed Mr Thomas after wearing gloves and arming themselves with knives and confronting him in the street in the early hours of July 23 last year.
They were accompanied by their driver Jamshaid and Saif Shazhad, 19, who was convicted of manslaughter after he helped Roberts and Griffiths chase Mr Thomas down Holmesdale Street and Corporation Road in the Grangetown area of Cardiff before he was killed.
Mr Thomas suffered multiple stab wounds and died from his injuries shortly after, just two days short of his 21st birthday.
Roberts pleaded guilty to murder during his trial, while Griffiths and Jamshaid were convicted of the offence and Shahzad of manslaughter.
At their sentencing on Friday, Mr Thomas' sister, Ashanti Esekhaigbe, read a statement on behalf of their family, calling the men who caused his death "cowards".
She said "We will remember Malaciah as he was, a loving son happily planning his 21st birthday celebrations.
"All we can say about those who took his life is that they are cowards."
Mrs Justice Nerys Jefford said the attack on Mr Thomas was "ferocious", and had happened after Roberts fell into a jealous rage over girlfriend Miss Davies' two-timing him with Mr Thomas.
The judge said: "The whole attack was the product of a jealous rage.
"It was caught on CCTV and what was seen was terrifying."
Roberts, of no fixed abode, and Griffiths, of Newport Road, Cardiff, were both jailed for life with a minimum of 25 years.
Jamshaid, of Moore Close in Ely, Cardiff, was jailed for a minimum of 11 years, while Shahzad, of Fidlas Road, Cyncoed, Cardiff, was jailed for seven years and six months.