Lily Allen Thanks ‘Friends and Family Who Showed Up’ to Make Her 40th Birthday ‘Special’ amid ‘Tricky Circumstances’

• Lily Allen shared a photo of her birthday cake on Instagram on May 4, two days after turning 40
• The singer thanked those who showed up to make the day “a special one under some tricky circumstances”
• Sources confirmed to PEOPLE in February that she and David Harbour had separated after four years of marriage

Lily Allen is grateful for her loved ones.

On Sunday, May 4, just two days after celebrating her 40th birthday on May 2, the singer shared a photo of her birthday cake on Instagram. In a heartfelt caption, she thanked those who helped her celebrate the occasion.

“Thank you to all my [beautiful] friends and family who showed up for me and made my birthday a special one under some tricky circumstances. Love you all,” she cryptically captioned the post, while tagging a few people, including her Miss Me? podcast co-host Miquita Oliver.

Allen’s birthday cake was covered in white frosting and decorated with fresh fruits including strawberries, blueberries and halved figs. Her first name and the number “40” were written in cursive lettering with pink icing. The cake was also adorned with pink flowers and covered in a light dusting of powdered sugar.

Oliver shared a photo of the cake on her own Instagram page, writing, “HAPPY 40th BIRTHDAY SCHMILLY BON BILLY!! We love you Lily. Hope we celebrated you good and proper.”

Several famous friends shared birthday wishes for Allen in the comments section of her post, including “Unwritten” singer Natasha Bedingfield, who wrote, “40 is the best.”

On her actual birthday on May 2, Allen shared a carousel of sultry snaps on her Instagram feed with the caption, “Happy Birthday to me.” The photo set began with a photo of the “Smile” singer looking at the camera while leaning against a wood-paneled wall as she sat on a sofa.

The English pop star wore a sheer baby blue spaghetti top accessorized with two statement necklaces. She rocked a burnt orange bob with bangs and accessorized with a pair of oversized sunglasses.

For her second selfie, Allen angled the camera toward her body and turned her face to the side. The Instagram carousel also included images of the singer moving the camera even higher and zooming in on her body.

Multiple sources confirmed to PEOPLE in February that Allen and actor David Harbour had separated after four years of marriage.

Later that month, Allen confirmed that she had a recent stay at a treatment center, but said she was in a “stronger place” following a time of “emotional turmoil.”

Sources told PEOPLE that Allen was “devastated and not in a good place” following the breakup with Harbour, 50. The insider added that the split has also been “very hard” on her daughters, Ethel Mary, 13, and Marnie Rose, 12, whom she shares with ex-husband Sam Cooper.