Actor and entrepreneur Blake Lively said she’s “mortified” about her joke about Kate Middleton‘s “Photoshop fails” — with the apology coming after the Princess of Wales confirmed Friday that she has undergone treatment for cancer.

“I’m sure no one cares today but I feel like I have to acknowledge this,” Lively said in a message shared Friday on her Instagram account. “I made a silly post around the ‘photoshop fails’ frenzy, and oh man, that post has me mortified today. I’m sorry. Sending love and well wishes to all, always.”

On March 15, Lively had posted a comically edited photo promoting her Betty Buzz beverage line, showing her sitting poolside with a can of Betty Booze with an enlarged thumb and a lemon floating above her head. In the since-deleted Instagram post, Lively had written, “I’m so excited to share this new photo I just took today to announce our 4 new @bettybuzz & @bettybooze products! Now you know why I’ve been MIA.”

That was a reference to visual anomalies in a photo released March 10 by the Royal Family depicting Middleton and her three children, which prompted AP and other news agencies to pull the image from their services. Middleton subsequently acknowledged, “Like many amateur photographers, I do occasionally experiment with editing.” The controversy led to fevered speculation about Middleton’s prolonged absence from the public eye. Amid conspiracy theories about the princess’ whereabouts, celebs including Jimmy Kimmel and Jamie Lee Curtis called on people to respect Middleton’s privacy.

In a video statement released Friday, Middleton said her cancer diagnosis was discovered following abdominal surgery and she is now in the “early stages” of preventative chemotherapy. “It has been an incredibly tough couple of months for our entire family, but I’ve had a fantastic medical team who have taken great care of me, for which I am so grateful,” Middleton said in the video.