The 38-year-old reality star - who has Mason, seven, Penelope, five, and Reign, two with her former partner - is now in a relationship with new beau Younes Bendjima, but in 'Keeping Up wit the Kardashians' scenes filmed before their romance blossomed, Kourtney phoned her ex to tell him she was seeing someone new, out of "respect".
However, the courtesy call backfired as 34-year-old Scott - who is believed to be jealous of his former girlfriend's new romance, despite now dating 19-year-old Sofia Richie - began yelling at her over the phone.
Speaking in her confessional on the E! reality show, Kourtney said: "Last night I went to dinner with a guy and was photographed and I just felt like I should give Scott a heads up out of respect, even though he hasn't done the same to me in the past. But the photos never ended up coming out in the end so it was pretty much all for nothing."
And sister Khloe, who had witnessed the phone call, added: "He was screaming at the top of his lungs."
Meanwhile, Kourtney recently slammed Scott for being photographed with a bevy of beauties before he entered a relationship with Sofia, and in a scathing attack, she called his women "hookers".
She said: "Why can't he get it together? I have to handle it when he's out photographed with a different hooker every day."
Kourtney's mother Kris Jenner implied that Scott was jealous after she jetted off for a girls' trip to Mexico and he was acting out.
She said: "I think he was jealous. Because you were having fun, spending time with other people."
However, Kourtney insisted that Scott - who reportedly cheated on her in the past - had no right to be jealous.
She said: "Well, that's really not fair. It's just like, I can't even live my life. I can't even go anywhere. He needs to get a f***ing life and leave me alone.
"All he does is try to make everybody else feel bad for him and try to make me look like the bad guy in the situation when clearly I'm not, from 10 years of this going on."