The 36-year-old reality TV star dumped her partner of nine years recently after he was spotted with ex-girlfriend Chloe Bartoli in the South of France and she was livid following his latest indiscretion.
A source told TMZ that Kourtney is especially angry because the party at Scott's Beverly Hills bachelor pad was held just hours after she allowed him back into their Calabasas home to see their three children.
The insider said: ''She thinks he's rubbing her nose in the breakup.''
Kourtney and Scott, 32, have children Mason, five, Penelope, three, and Reign, seven months, together.
Meanwhile, it was recently claimed that Scott isn't worried about being dropped from Kourtney and her family's reality TV series 'Keeping Up with the Kardashians'.
A source said: ''He's gotten away with so much for so long, he believes he's immune to anything they can throw at him. But the truth is, it's not going to take much for the Kardashians to ruin him completely.''
Kourtney and her family, including mother and manager Kris Jenner, are prepared to turn their backs on Scott for good unless he seeks treatment in rehab.
The insider told Star magazine: ''They aren't messing around. If it weren't for the Kardashians, Scott would be a broke, drunk nobody.
''Everyone in the family feels completely betrayed by Scott. Kris truly looked at him like a son.''
The former restaurateur has spent three brief stints in rehab over the past year, but is still struggling to get his life back on track following the deaths of his parents, Bonnie and Jeffrey, within three months of each other in late 2013 and early 2014.
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