The make-up free star, who was wearing a pink baseball cap, failed to raise a smile as she sat in the driver’s seat chatting on her phone.
The pair had been planning to announce it on Sunday - Mother’s Day.
"Allegedly the other half of her family leaked her story so she had to announce it.”
The spokesperson added that the only people who knew about the news was himself and Blac’s good friend Amber Rose, and said they could have done it to promote their show.
"The only people that knew from Chyna's side was myself and Amber. Her mother didn't even know. [Chyna's] moment was taken from her, which is really sad.”
Mirror Celebs has contacted a rep for the Kardashians for comment.