For the first time ever, Charlie Hunnam has gone into detail about why he accepted the leading role of Christian Grey in the movie adaptation of "Fifty Shades of Grey," and then backed out two months later.

Before Jamie Dornan was cast as Christian, the "Sons of Anarchy" actor shocked fans of his show, of E.L. James' erotic novel and even his FX series co-stars by accepting the role of the S&M-loving billionaire.

"I wouldn't have signed up in the first place if I didn't want to do it," Hunnam told Us Weekly at a Television Critics' Association party in August. "It was a really, really difficult time in my life. I had already been attached to 'Crimson Peak' for about 14 months, which I said, I was going to do with Guillermo [del Toro]."

According to Hunnam, he "fell in love creatively" with "Fifty Shades of Grey" director Sam Taylor-Johnson.

"I fell in love with the character and started seeing him and becoming intoxicated, which is the way I work: I find a character I love and I start thinking about it all the time," he said.

Christian, however, wasn't the only character on Hunnam's mind. He also had his signature role of biker Jax Teller on "Sons of Anarchy" and his role in del Toro's upcoming film as a "dorky dude," as Hunnam described to Yahoo UK, named Dr. Alan McMichael.

"I was going to finish [filming] 'Sons' at like 11 p.m. Friday night, get on the plane Saturday morning to Vancouver for 'Fifty,' missing the whole first week of rehearsal, and start shooting Monday morning," Hunnam explained. "And I was going to shoot that film, wrap that on the Wednesday and the following Monday I was going to start shooting 'Crimson Peak' in Toronto."

All of this proved too much for the 34-year-old actor.

"I just had like ... frankly, something of a nervous breakdown," he said. "... I just said, 'I can't ... I can't ...'"

Hunnam was scared of disappointing in such a high profile movie.

"... because 'Fifty's' going to be massive, it's going to be huge, I really didn't want to fail on such a grand scale, and I just couldn't transition from Jax Teller to Christian Grey in 48 hours," he explained. "It's painful because I loved the character and I wanted to do it. I'm also a man of my word."

The actor formerly (and briefly) known as Christian Grey added that it was a "sh** situation" and he was "really, really sorry" he had to make his decision.

"It was one of those damned if you do, damned if you don't situations," he said.

"Fifty Shades of Grey" hits theaters Feb. 13, 2015.

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