Madonna Thanks Fans for Support During Custody Battle

— -- Madonna has taken to social media to thank her fans for their support during what she has publicly called a “challenging” time in her life.

The music superstar posted a photo on Instagram over weekend of a letter she received from her fans.

“WE ARE HERE. As we always have been, and always will. Whatever the things you’re going through right now (We are aware that we don’t know everything), no one else than your true fans keep their minds and hearts with you on them,” read the letter, signed by “Your Rebel Hearts.”

Madonna -- who is undergoing a custody battle with ex-husband Guy Ritchie over their teenage son, Rocco – captioned the photo, “Thanks soooooo much for this! It means a lot to me! One word of. kindness it can save me!”

The 57-year-old “Express Yourself” singer has opened up to her fans publicly about her struggles before, telling fans at a Mexico City concert earlier this month, “I too go through challenging times in my life ... right now is one of them.”

Madonna and Ritchie are set to appear in a New York City courtroom for a second hearing next month.

Rocco has reportedly missed school since visiting his London-based director dad in December. A New York City judge ordered Ritchie to return Rocco to New York after Madonna reportedly appealed to the court.

Guy Ritchie declined to comment to ABC News on the custody matter.

Last week, Madonna posted a photo of herself on Instagram with the caption, "Moving Forward...........nowhere else to go."

Another of Madonna's four children - daughter Mercy James - was also in the spotlight over the weekend.

Madonna led a chorus of “Happy Birthday” for her daughter's 10th birthday onstage at a “Rebel Heart” show in Miami.