Westbrook had two central grievances with her erstwhile protege.
Firstly, he had promoted a vitamin pill brand called Sugar Hair Bear on his channel, a direct competitor to her own company, Halo Beauty. This came after he had previously declined to promote Halo as a favour to her out of responsibility towards his teenage fanbase, only to then apparently abandon his scruples and back a lucrative rival.
Secondly, Westbrook expressed disapproval over an incident that she said had taken place over dinner in a restaurant in which Charles spoke admiringly of a waiter. When he was informed the man was straight, Charles allegedly responded with the words:
It doesn't matter, I'm a celebrity.
You tried to trick a straight man into thinking he's gay and somehow you're the victim. It's really disgusting to manipulate someone's sexuality, especially when they are still emerging into adulthood and don't quite have everything figured out.
You are using your fame, your power, your money to play with people's emotions. You're threatening to ruin them, you're threatening to embarrass them, and you're doing that to have them behave sexually in your favour even if they're straight.
Charles responded with an eight-minute video of his own (see above) in which he apologised but did not specifically address either of her allegations, causing many to dismiss it as insufficient and insincere.
Fans meanwhile delighted in the conflict, with many pledging their allegiance to Westbrook by following her or unfollowing him.
At the time of writing, a YouTube Live feed tallying the exchange has James Charles on 13.8m followers and Westbrook on 9.1m. The former had 16.5m followers before the controversy dropped, while the latter had just below 6m, meaning he has lost 2.7m as a result of the furore while she has gained more than 3m.
Jeffree Star, one of the most influential figures in the YouTube beauty community, has since expressed his support for Westbrook tweeting:
Shortly afterwards, Star had to correct himself, so rapidly was Westbrook's follower count booming:
And then again!
He later joked that the "beauty community is burning to the ground" but Tati Westbrook was striking a more sombre note on Sunday night.
There won't be a video tomorrow. My heart is still too heavy. I feel like I need to remind you that we can hold tru… https://t.co/fMrRKGWz0W
Honestly, who knew cosmetics reviews could inspire such high drama?
At this rate, historians of the future will find themselves picking through the rubble and detritus of a fallen world, scratching their heads and asking each other in bewilderment how the Charles-Westbook War of 2019 ever got started in the first place.