Director Says Making Fifty Shades Was ‘Like Walking a Knife Edge’

Not unlike the heroine in her hotly anticipated upcoming movie, director Sam Taylor-Johnson feels “wrung dry” by her whirlwind experience with Fifty Shades of Grey.

“I’m literally going out of my mind,” she tells Red for its March issue, which hits U.K. newsstands Jan. 29. “I have seen this film over a thousand times and … the nuances within – the tiniest shift, look, blink of an eye – can make all the difference and flip it into the wrong territory. It’s like walking a knife edge.”

Much like Anastasia Steele’s tangle with the cunning Christian Grey, Taylor-Johnson, 47, says she’s been breathless ever since she signed on for the project.

“The moment I stepped out of the meeting, I stepped onto one of those bullet trains. The doors closed and I couldn’t get off. The speed, the velocity, was unbelievable. I need to get off and breathe and think about something else,” she says.

One thing that made the filming process a bit easier? Jamie Dornan, who apparently made a very cooperative Christian Grey.

“Jamie’s funny because he doesn’t seem to feel any of the pressure. Or show he feels it,” she says. “Everything washes over him and he’s constantly happy. He’s such a sweet and lovely man.”

That attitude came in handy when they met with various folks in the fetish world for, you know, research.

“Jamie and I had to sit and meet various dominants and dominatrix, just to make sure we understood that world; so that we in no way portrayed it incorrectly,” she explains.

With Grey’s set to hit theaters on Feb. 13, Taylor-Johnson can finally start to think about taking some time off to be with her family, which includes husband Aaron Taylor Johnson, who is 23 years her junior – and don’t even think about analyzing their age difference.

“Tell them to f— off,” she tells the magazine of negative comments they still receive. “If you love someone, you love someone. It doesn’t matter; age, color, c’mon!”

Now, she simply can’t wait for them to spend more time together.

“I don’t want to do anything,” she says. “I feel wrung dry and I need to find some building bricks again. I don’t think I could even compose a picture right now. My creative brain has to shut down for a second. I need to be at home, put my feet up, feel calmer, eat well and hang out with the kids.”

This article originally appeared on People.com