Actress and former "Dancing with the Stars" contestant TATUM O'NEAL can relate to BRITNEY SPEARS on a whole new level now that the court has ordered the embattled pop star to hand over physical custody of little SEAN PRESTON, 2, and JAYDEN JAMES, 1, to ex KEVIN FEDERLINE.

No stranger to child custody battles herself -- with ex JOHN McENROE -- Tatum shared her views on the subject with ET's own THEA ANDREWS on the set of her new movie, 'Saving Grace.'

"[Britney] needs to think she needs some help; no one can tell her," says Tatum. "She can get better ... but it's going to be hard, and she'll do it publicly, and that sucks."

"I went through my problems too, and I relate to her, and I feel really sad for her," continues the former child star. "I had to realize that I had to take my own responsibility for everything, whether it was anger at my dad, or anger at my ex-husband ... I did all the things that she doesn't want to do -- I did the drug testing, I did the parenting classes ... it was very humbling. But I wanted those kids more than I cared about getting [back at anybody]. I wanted those kids in my life because my mother lost custody of me when I was six years old. So I relate, you know, and I feel sad."

In 'Saving Grace,' PENELOPE ANN MILLER and MICHAEL BIEHN play Bea and Landy Bretthorse, a couple whose life in a 1950s-era Missouri town is thrown into chaos when Landy's sister Grace (Tatum) is released from the local asylum and comes to live with them. Shot on location in the South, the film marks the writing-directing debut of veteran singer and "Hawaiian Eye" star CONNIE STEVENS, who based the story on a personal experience when she was visiting relatives in Boonville, MO, in 1951 during severe floods that play a pivotal role in the film.

Watch ET for more with Tatum!