The “How to Murder Your Life” author, 37, announced on Instagram Wednesday that she hasn’t taken Adderall in two years, and told Page Six it’s because she left the city.

“Physical distance from my doctors in New York helped the most. I loved my psychiatrist; he was so kind. He was forty thousand years old, up on East 79th Street,” she told us via email, “but he gave me anything I wanted.

“I traveled the world for 3 years and that finally got me away from him,” she said. “I’ve never called his number again.”

Marnell has been extremely candid with her struggles with substance abuse — she once copped to snorting heroin and taking a Xanax before passing out in a bath — but asserted she doesn’t miss Adderall at all.

“You gotta dump a drug like you dump a man and never look back. Adderall was my abusive boyfriend,” she explained. “I was obsessed. I was going to get a crack rock glazed and set and wear it like a diamond ring!

“Now I’m out of my ugly 18-year relationship; I’m replacing all that.”

Marnell has been “replacing” her addiction with human contact, choosing to hang out with new people every day, including those she might meet on dating app Raya.

“It’s great to be in New York, surrounded by media and art world friends. I miss having co-workers! And I’m dating,” she shared. “I’m looking for a therapist for the first time to help me with my ‘human connection’ problems.”

Though Marnell has dropped the prescription drug prescribed for attention deficit disorder, she played coy when asked if she’s totally sober.

“I believe the poet Rumi said, ‘Out beyond crippling addiction and 12-step recovery, there is a field. I will meet you there.’”

In that field, Marnell found time to write her next book, “The Bored and the Beautiful,” which will be a creative nonfiction collection of autobiographical essays.

“I’m writing my Fantasia; I’m writing ‘My Beautiful Dark Twisted Fantasy,’” a reference to Kanye West’s album.

“The Bored and the Beautiful” will detail Marnell’s 30s — her self-described “successful time” after her career launched.

“My weird years in Tribeca when I lived next to David Blaine’s magic studio … when I kept falling down the stairs of my Cortlandt Alley loft,” she added. “I go to Art Basel…two jungle rehabs in Thailand… Biarritz [France]… Riff Raff is in it.

“It’s chick lit noir.”