ASANSOL, India — Sitting there, waiting to take the very last bath of her life, Nisha Kapashi was the happiest she had ever been.

The New York-born former fashionista, 30, was taking part in Diksha, the sacred ceremony of renouncing one’s materialistic life, in order to become a Jain nun.

“Imagine an Indian wedding, well, it was just like that,’’ the ex-quintessential Manhattanite told The Post of the emotional January ceremony.

“I was getting married to the Jain nun philosophy, and I was treated like a bride,” she said. “I had my last bath ever, and I had my hair shaved off as a symbol of renouncing my old life. People believe we have our hair plucked out, but [it’s] only a few strands. The rest is shaved.”

While brought up within the ancient Indian religion as a child, Kapashi said she never imagined the day would come. Seven years earlier, Kapashi had been living in the Big Apple fulfilling her dream of working in the fashion industry.

Born in Poughkeepsie, she attended the Fashion Institute of Technology, and then landed an internship at Kate Spade and a high-paying job at J.Crew.

She had a closet full of high-end fashion labels, and her parents put her up in a lavish, one-bedroom apartment on Sixth Avenue and 34th Street, near Macy’s.

“At 23, I was finally living the life I had dreamed about as a teenager,” Kapashi said.

“I used to eat my lunch near the office on Union Square every day and eat at some of the top restaurants at night with my friends,” she said. “I was never a party animal and I never drank alcohol, but I loved good food, especially Italian food and pasta.”

But not even all the pasta and Prada in the world could fill the emptiness that was growing inside her, Kapashi said.

“I couldn’t understand why I wasn’t the happiest person in the world,’’ the nun said.

“I was trying to be fashionable and successful, but the more I did so, the emptier I felt. Slowly, I began to change. I stopped caring so much about how I looked. I began to wear simple outfits . . . and no makeup. The more changes I made, the better I was feeling.’’

Kapashi resigned from her job and began meeting with Jain study groups in Queens once a week in 2011. She eventually moved to India and formally studied to become a nun.

Jainism is a major religion in India, along with Hinduism and Buddhism. Her family originated from Mumbai.

Now, as a nun, “we sleep for six hours a night, meditate for 90 minutes a day, and we study the Jain philosophy for 15 hours a day,” Kapashi said. “We live a nomadic existence in India. I have no possessions. I have nothing, but I’ve never been so happy.”

Instead of Gucci clothes and Fendi handbags, she now flaunts “a water holder and bowls made out of pumpkin for food; an ogho, which is a brush we use to wipe away any living being as we walk; a walking stick and white material for our clothes and bedding.”

“We don’t even have any shoes,” said Kapashi, a former fan of high-end footwear.

“I have no money, not even a bank account.

“I have committed to a life of celibacy and simplicity for the rest of my life,” she said.

“This is my life now — and it’s the ultimate happiness.’’

Additional reporting by Chris Perez