Click on photos below to meet the cast of Made in Chelsea series six.
Jamie, who has shown strong interest in both girls, was caught out when Phoebe discovered that the playful character had slept with her "arch-enemy" Lucy, just days before asking Phoebe out on a date.
As the tryst emerged, the feisty girls fired insults at each other at the Bollywood-themed birthday party of their co-star Victoria Baker-Harber.
"You are literally the most unpleasant girl I've ever met," Lucy said to Phoebe, before making fun of the fashionista's outfit. "Your nose ring looks really weird."
"Your dress looks tacky," retorted Phoebe.
The pair's co-stars and fans were quick to take sides and jumped to each girl's defence on Twitter.
"@imlucywatson is about to rock this episode #teamlucy," wrote Cheska Hull, next to a photo of Lucy looking stunning in her exotic costume.
Jamie and Lucy, who end up kissing at the end of the episode, were clearly embarrassed at watching the party scene played back.
"OMG I JUST DIED. That kiss @JamieLaing_UK," Lucy tweeted to Jamie, to which the blonde boy replied, "worst ever".
"JUCY? @imLucyWatson," joked Jamie on Twitter after the episode.
The fun-loving cast member got his fair share of telling off from fans including Holly Willoughby.
"JAMIE!!!!! #mic," wrote Holly, followed by "@JamieLaing_UK never have I been so pleased and then so disappointed!"
Drama and scandal escalated on the show when Jamie took it upon himself to pass on words of advice to friend Alex Mytton, who was involved in his own love triangle with Binky Felstead and Fran Newman-Young.
After Alex invited both girls to his house for dinner, Jamie suggested he get rid of the one he didn't fancy, Fran, by lying to her and saying he had a rugby injury.
"Would you really take relationship advice from me #madeinchelsea," tweeted Jamie, in his defence.
"Least I'm good at excuses, if you need any give me a shout!!" joked Alex on Twitter.
The cattiest comment of the night came from birthday girl Victoria, who poked fun at Cheska dancing in her white Bollywood costume.
"Cheska's obviously wearing the bride dress because she's never going to be the bride," said Victoria.
Cheska set the record straight on Twitter, writing, "For the record @victoriaBH I have been in a loving relationship for over a year So thank u for proving you truly are a horrible mean girl!"