Avril Lavigne Announces New Music with Heartfelt Letter to Fans: 'I Felt Like I Was Drowning'

Avril Lavigne is officially coming back — and fans are ecstatic.

The singer, 33, announced in a heartfelt open letter that her first single “Head Above Water” will drop on Sept. 15 and that she hopes “more than ANYTHING to be back up on stage.”

“Thank you for waiting so patiently as I fought through and still continue to fight the battle of my lifetime,” the “I'm with You” singer wrote of her long, debilitating battle with Lyme disease.

“[‘Head Above Water’] is the first song I wrote from my bed during one of the scariest moments of my life. I had accepted death and could feel my body shutting down,” she adds. “I felt like I was drowning. Like I was going under water and I just needed to come up for air. Like I was in a river being pulled in a current. Unable to breathe.”

On Saturday, Lavigne shared a photo showing herself fully submerged in water, hinting about the release of the single, which she says she wrote while in the arms of her mother.

“My mother held me. In her arms, I wrote the first song that I am releasing to tell my story,” the singer continued in her note. “I later met a beautiful soul, Travis Clark, and we sat down at the piano and sculpted the rest of the song.”

Lavigne added that while the past few years have been “the worst years of my life,” she says she was able to “turn that fight into music I’m really proud of.”

“Words and lyrics that were so true to my experience came pouring out of me effortlessly. Truly… by keeping my spirits up, having goals to reach and a purpose to live for, my music helped to heal me and keep me alive,” the Ontario-born artist says.

The letter comes just two weeks after she shared behind-the-scenes footage of her upcoming music video, presumably for music in the new era, and tweeted a photo captioned, “I can’t wait for September.”

Lavigne also changed her Twitter cover photo and profile picture, in addition to adding a mosaic photo depicting the art of her new single cover on Instagram.

In her letter, Lavigne emphasized that she decided to be honest and open about her struggle with Lyme disease because “a single bug bite can f— you up hard” and “people aren’t aware that Lyme must be treated almost immediately.”

“I have decided to be truthful about my struggle, open and more vulnerable than ever before. And to be honest, part of me doesn’t want to talk about being sick because I want it to all be behind me, but I know I have to,” the singer added.

Earlier this year, a source close to Lavigne told PEOPLE that the singer-songwriter “purposefully lived a quiet life” while recovering from Lyme disease, which she was diagnosed with in 2014.

“I could barely eat, and when we went to the pool, I had to leave and go lie in bed,”she told PEOPLE about her disease for a cover story in 2015. “My friends asked, ‘What’s wrong?’ I didn’t know.”

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In her letter, she explained that The Avril Lavigne Foundation website will feature resources for people to prevent the disease and will aim to accelerate Lyme research.

“We’re about to launch an initiative that YOU can help us with — so that together, we can help more individuals affected by Lyme disease get the treatment they desperately need to come out the other side of this insidious disease,” she wrote.

The singer thanked her fans for waiting patiently and supporting her while she recovered.

“I’m so excited to be returning with new music and to have you on this journey with me,” she writes. “Let’s do this! New era!”