"She had no idea that something of this severity would hit her out of absolutely nowhere," says a source

Credit: Imeh Akpanudosen/Getty

Chris Brown has yet to publicly confirm reports that he’s a father, but his longtime girlfriend Karrueche Tran is already moving on.

“Chris is still trying to get ahold of her and is calling and texting nonstop,” says a source close to Tran, who added the singer initially denied the baby was his. “She’s not answering and doesn’t have any plans to in the near future. She doesn’t want any part of the drama.”

And though Brown, 25, and Tran, 26, are infamous for their on-and-off relationship, “they’ve been pretty solid for the past year or two,” says the source, which means “he likely cheated on her.”

After being “totally blindsided” when the news broke, the model partied with pals – including Christina Milian – Wednesday night at Warwick in Hollywood after grabbing dinner at Hyde Sunset Kitchen + Cocktail.

“She was hanging out with her friends, casually drinking cocktails and dancing,” says the source. “She was in amazing spirits.”

While the pal says Tran is “completely mortified” by the situation, she “is honestly trying to leave it behind her and move on with her life. She’s seeing it as an opportunity to start fresh.”

According to TMZ, the mother of the 9-month-old baby girl is a former model named Nia.

Brown’s rep has not responded to requests for comment.

Tran Tweeted a response Wednesday to reports about Brown’s baby, wishing him the “best of luck.”