Madonna has taken to Instagram to speak out as her custody battle with ex-husband Guy Ritchie continues. The 57-year-old singer and Ritchie are reportedly gearing up to go to court over custody of their 15-year-old son Rocco, who has refused to return to the US since December.

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"It's possible to be an entertainer and a good mother!" Madonna captioned a throwback photo featuring herself and her four children, Lourdes, 19, Rocco, 15, David Banda, 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!”

The post comes just days after the singer referenced ‘challenging times’, during a concert in Mexico. "We all go through challenging times in our life, and that includes me," Madonna said (via Billboard).

More: Madonna Addresses 'Challenging Times' During Mexico City Concert

"I, too, go through challenging times in my life, and right now is one of them. Sometimes I think I can't do a show. I don't have the energy, I don't have the strength. I come out here tonight and I can see your faces, and I look into your eyes and I see so much love and it gives me strength. So thank you. You are rebel hearts. I feel your hearts beating with mine.”

Madonna spent Saturday night with her former husband Sean Penn, attending a charity bash in aid of Help Haiti Home foundation. The former couple split in 1989 after four years of marriage, but are said to still be very close friends.

More: Guy Ritchie Hires Lawyer In Preparation For Custody Fight With Madonna

According to Variety, Madonna paid tribute to her ex in a speech saying: “I want to say Sean, I love you, from the moment that I laid eyes on you. I just wish you'd stop smoking cigarettes.”

The singer was accompanied to the gala by her daughter Mercy James and son David Banda. The event raised $6 million for the cause and afterwards Madonna shared a photo of herself and Penn on Instagram writing: ‘Tonight was Fire! thanks to Sean and everyone at J/PHRO!!!!! We raised 6 mullion dollars for Haiti #rebelhearts (sic)’

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