Madonna in March 2015 in Los Angeles. Credit: Kevin Mazur/Getty Images for iHeartMedia

Madonna ranted about being "a good mother" in an Instagram post on Saturday, January 9, as her custody battle with ex-husband Guy Ritchie continues.

"It's possible to be an entertainer and a good mother!" the pop superstar, 57, captioned a throwback photo that showed her with her four children — Lourdes, 19, Rocco, 15, David, 10, and Mercy, 9. "Too bad we don't live in a society where many encourage strong independent single working moms! The next great frontier!"

Madonna has been fighting with her ex-husband over custody of their son Rocco, who hasn't returned home to NYC after spending time with his dad in London. On January 8, a source exclusively told Us Weekly that the "Material Girl" songstress is at "her wit's end" over her estrangement from Rocco and her ongoing battle with Ritchie, 47.

“She has been crying constantly over what’s going on with Rocco,” the insider told Us.

Ritchie and Rocco were spotted wearing matching outfits as they rode bikes together in London on Saturday.

As previously reported, the pop queen's son refused to board a flight back to the U.S. for Christmas, choosing to spend the holiday with his British film director father in the U.K. On December 23, a New York judge ordered the teenager back to Manhattan, but a lawyer for Ritchie maintained that her son "has expressed very clearly" that he wants to stay with his dad.

“Rocco is a typical 15-year-old who wants to do what he wants,” the insider explained. “This entire thing is 40 percent Rocco and 60 percent Guy," the source said, adding that “Guy is trying hard to mess with her again."

Ritchie and Madonna divorced in 2008, after eight years of marriage.

"Madonna has been actively doing all she can to get her son Rocco home and back to school in New York," a second source previously told Us. “Rocco, along with Madonna’s other three children, have never been away from her for any extended period of time until daughter Lourdes went away to college last year."

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