PHOTO: Selena Gomez/Instagram

Selena Gomez had a busy summer—releasing new music, reportedly moving in with her boyfriend—but her fans may have noticed that the star wasn’t out in the public eye much despite having new songs to promote. This morning, Gomez revealed why: a few months ago, she received a kidney transplant, which she needed due to complications from lupus.

“I found out I needed to get a kidney transplant due to my Lupus and was recovering,” Gomez wrote on Instagram of her extended absence over the last few months. “It was what I needed to do for my overall health.” Gomez has been public about her battle with lupus, a disease that causes the body’s immune system to attack its own organs and tissues, since being diagnosed in 2014 and undergoing chemotherapy to treat it in 2015. An organ transplant is a major surgery, and the gravity wasn’t lost on Gomez, who also wrote: “I want to publicly thank my family and incredible team of doctors for everything they have done for me prior to and post-surgery.”

But the most incredible part of Gomez’s story has to be her donor, longtime friend Francia Raisa (that’s her in the photo, in the hospital with Gomez). “She gave me the ultimate gift and sacrifice by donating her kidney to me. I am incredibly blessed. I love you so much sis.”

One of the most selfless and brave things a person can do is donate an organ, and it’s amazing to see Gomez publicly acknowledging that (with 2.1 million likes so far on the post, it seems Raisa is getting the recognition she deserves).

Gomez’s fans are already flooding the star with love and get-well-soon wishes, but as she writes herself, the best way to show her support is to get educated about lupus, a still-misunderstood disease.

To learn more, Gomez recommends checking out the Lupus Research Alliance.