The actress, who plays Zainab Masood in the BBC One soap, was left in tears while filming her character's domestic violence scenes with co-star Ace Bhatti, who plays manipulative doctor Yusef Khan.
"It's very draining emotional stuff," she told The People. "I'm putting myself into this very dark place which I know sadly is a reality for so many women. Zainab's confidence has been steadily eroded. She's feeling isolated and has fallen under Yusef's control.
"He wants revenge. She is totally in his power. I had to show this can happen to any woman, no matter how strong she seems. Zainab was strong and not naive, but a woman is vulnerable if the man hits the right psychological weak spots.
"But both Ace and I have found it hard to do. I've known Ace for a long time and we're good friends. He has been wonderful to work with on this and very concerned about me all the way through."
Wadia has been getting advice on the storyline from the Roshni refuge in Birmingham, which offers support for Asian women and children suffering from abuse. She is also the refuge's patron.
Wadia recently confessed that she wants Zainab to reunite with estranged husband Masood next year.
> EastEnders' Yusef will get worse, warns Nina Wadia
> EastEnders' Masoods 'at centre of shock fire'
> EastEnders star Nina Wadia wants Zainab friendships
> Read Digital Spy's recent interview with Nina Wadia
> Read more EastEnders spoilers and news