Mary-Louise Parker and Billy Crudup’s Son, William, Is All Grown Up: Pics

Mary-Louise Parker and her son, William Crudup, attend the 'When We Rise' New York City screening event at the Metrograph on February 22, 2017. Credit: Jamie McCarthy/Getty Images

Not so little anymore! Mary-Louise Parker and ex Billy Crudup’s son, William, looked more grown up than ever while posing for photos with his famous mom at a Wednesday, February 22, screening for ABC’s new show When We Rise in New York City.

The 13-year-old, who rocked long hair at the event, looked polished in a corduroy blazer paired with matching pants and a plaid button-down shirt. Parker, 52 — who stars on the LGBT-focused miniseries — was equally stylish in a white top teamed with a black skirt, sheer tights and chunky heels.

As many are well aware, Parker was seven months pregnant with William when Crudup, now 48, left the Weeds actress in 2003 for his Stage Beauty costar Claire Danes.

Parker vaguely alluded to Crudup’s infidelity during a November 2015 interview with the Today show’s Savannah Guthrie. "[It’s] private to me and will always remain so,” she said at the time.

Despite her heartbreak, the South Carolina native is grateful for her relationship with Crudup because it resulted in her biggest blessing: William.

"It was something that I had waited for all my life," Parker said of motherhood, as detailed in her 2015 memoir, Dear Mr. You. "I wanted a baby my whole life. I was a little girl who wanted that baby."

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