Jessica's 29th birthday was on Friday and she had planned a Barbie-themed birthday bash to celebrate.
But she wasn't in a festive mood after Tony broke up with her the night before the party.
"She was surprised. She wouldn't have planned a party if she knew this was coming," a source close to Simpson tells E! News. "They're both going their separate ways."
A bummed-out Jess canceled the fete, but Tony went clubbing that night...
He hit MyHouse with a group of 14 friends on her birthday. An onlooker tells E! that "quite a few girls stopped by his table." On Saturday, Tony was spotted hanging poolside with pals at the Roosevelt Hotel.
Despite the birthday breakup, Jess seems to be keeping the faith. "Everyone needs to know that hope floats...grab the strings and pull it back to you," she twittered on Sunday.
Maybe she should call her ex-hubby, Nick Lachey, who's also newly single, for some moral support?