Ricky Martin is barely sleeping these days.

What is keeping him up is his biggest acting role to date - a part in American Crime Story: The Assassination Of Gianni Versace, which looks set to be one of the buzziest new prestige dramas next year.

Debuting in the United States in January, it will see the Puerto Rican pop star playing his first gay character, Antonio D'Amico, who was the partner of Versace - the Italian fashion designer murdered by serial killer Andrew Cunanan at his Miami home in 1997.

Edgar Ramirez plays Versace, Penelope Cruz is sister Donatella and Darren Criss is Cunanan.

The project feels deeply personal to Martin, who was once one of the biggest pop stars in the world, thanks to hits such as Livin' La Vida Loca (1999) and The Cup Of Life (1998).

Speaking to The Straits Times at a press day in Los Angeles last week, the 45-year-old becomes visibly emotional when asked why it means so much to him.

"I'm a gay man that lived in the closet for many years, and to see Gianni actually come out and sit down in front of a journalist to talk about his reality was something that moved me in many ways," says Martin, who came out in 2010 and is now engaged to Jwan Yosef, a 32-year-old Swedish-Syrian painter.

"Even though everybody knew about the relationship with Antonio, the fact they couldn't be as open as I am now with my relationship is something that frustrates me."

It has taken time for him to be ready to play a role like this.

"Before, I was not ready to do this kind of character," he says. But he has always related to "the ups and downs, the frustrations, the uncertainty and the fear of losing your career because of being a gay man", and notes that "a lot of men and women are still struggling over this".

This is why he jumped at the chance when contacted by Ryan Murphy, a producer on the widely acclaimed first season of the American Crime Story anthology series, The People V. O.J. Simpson, which led the Emmys last year with five wins, including for Outstanding Limited Series.

Just as with the dramatisation of the 1995 Simpson murder trial, Murphy hopes the second season, which has no Singapore air date yet, shines a light on broader social issues - in this case, homophobia in the police force, which Murphy says refused to put up Wanted posters for Cunanan in Miami, even though it knew he was likely headed that way.

Martin says: "When Ryan told me about this and the unfairness of the things that they went through, I said, 'I need to be part of this, I need to get this off my chest for personal reasons and I need to talk on behalf of many people that are unfortunately not able to feel as complete as I feel right now.'"

Playing D'Amico, who found Versace bleeding on the steps of the mansion after he was shot, is proving as emotionally taxing to him as it is exhilarating.

"I've immersed myself in this completely. I told my partner and my family to back me up because this is as serious as it gets in terms of the emotions I deal with every day," says Martin, who has nine-year-old twin sons conceived through a surrogate.

"I try to drive home (from set) and I open the windows and I scream, cry and laugh if I have to, before I walk into the house when my kids are awake," says the star, whose most high-profile English-speaking role before this was a stint on the soap opera General Hospital from 1994 to 1995.

He adds that even his experiences as a singer performing to crowds of up to 100,000 pale in comparison with the role in some ways.

"When I walk onstage and feel the energy of the audience, it's fantastic. But it is another thing to leave my skin to become someone else. My heart beats faster and I get goosebumps because I have never felt this in my life. And after 35 years in the business, I haven't felt as inspired as I am right now," he says.

Earlier that day, Martin spoke for the first time to the real D'Amico, 58, and Murphy credits the singer with helping convince Versace's former lover - who was initially scathing of the project after seeing images of Martin on set - to support the series.

Martin says: "The first thing that came out of my mouth was, 'I'm so happy we're talking. I just want you to know that this is being treated with the utmost respect and that I will make sure people fall in love with your relationship with Gianni. I want them to see the beauty and the connection that you guys had.'

"And he was extremely happy about it."