Credit: Christopher Peterson/BuzzFoto/FilmMagic

Talk about Kevin Federline's ghastly weight gain all you want.

"He doesn't care," his ex Shar Jackson told at HBO's post-Emmys party in Los Angeles Sunday. "The beautiful thing about him is that he could care less."

She said the 31-year-old dancer-turned-rapper is doing "good."

As his ex Britney Spears continues her Circus tour, he's been on the road looking after their sons Sean Preston, 4, and Jayden James, 3.

Jackson said that he still manages to phone the two children he has with her: Kori, 7, and Kaleb, 5.

"He calls them all the time," she told Us. "They have good long phone conversations. I’m like, 'Ok, that's good. Hang up the phone 'cause we have stuff to do.'"

Jackson said she is also proud of Spears — whom she once loathed. (Spears famously began dating Federline while Jackson was pregnant with Federline's second child.)

"She seems like she’s doing well," Jackson told Us of Spears, who was hospitalized twice in 2008. "Good for her."