Gossip Girl star Matthew Settle is expecting his second child, Us Weekly can exclusively reveal Credit: Dimitrios Kambouris/Getty Images

Rufus Humphrey is back to diaper duty! 

Matthew Settle is expecting a child with his girlfriend Maria Alfonsin, Us Weekly can exclusively reveal. The Gossip Girl alum has stayed mum about the pregnancy, but it was his former costar Kelly Rutherford that spilled the beans this week in NYC.

Rutherford, 46, let it slip that her former TV hubby, 45, was adding to his family during the Alice & Olivia + Domingo Zapata Celebrate CFDA Capsule Collection event on Tuesday, April 28. At the time, the actress listed who's on the guest list for her Children's Justice Campaign affair on May 12.

(Rutherford created the organization amid her brutal custody battle with ex-husband Daniel Giersch. Giersch was refused re-entry into the U.S. and now lives with their son Hermes, 8, and daughter Helena, 5, in France.)

"Marcia Cross, Ed Westwick, Vivica Fox, Selma Blair, and Lisa Rinna are all hosting. And Marianne Williamson and Lisa Bloom are speaking," she told Us at the bash sponsored by Bombay Sapphire. "I'm hoping Matthew can make it. He's getting ready to have a baby, so I don't know." She teased: "His loss!" (She also briefly mentioned it to Hollyscoop in February.)

Settle is best known for playing Rufus Humphrey on Gossip Girl (XOXO!) from 2007 to 2012. He already shares 6-year-old daughter Aven with his ex-wife model Naama Nativ, whom he split from in February 2010.