Hilarie Burton found it "really hard" to shoot her return to The Walking Dead universe.

The 42-year-old actress made a surprise return as Lucille in TWD: Dead City on 15 June, when Negan - who is played by her real-life husband Jeffrey Dean Morgan - hallucinated his dead spouse after suffering a head injury, and emotionally apologised for failing to keep his cancer-stricken wife alive.

And Hilarie has praised her husband's performance and genuine emotion in the scene, which was filmed just days after his father's death.

She told People magazine: "Please forgive me if I get upset. I just watched it. I didn't see it on Sunday. This was a really hard episode to shoot.

"What people didn't know is that, throughout this season, Jeff's dad was dying. He had died like six days before we shot this scene.

"Watching this man that I love so much hold that grief and really have to focus at work and hold it together, I wouldn't cry except I just watched it.

"It was really, really amazing to watch the person you love most in the world be able to do that. He was able to channel a lot of the grief he was feeling for his dad into this episode while not letting anyone down."

The former One Tree Hill star told how Jeffrey had been given a few days off from filming so the family "could go say goodbye to his dad" shortly before he passed away last July following a brief illness.

She added: "It really was a family affair. Everyone knew that he was dealing with this tragedy, but these storylines had been written well in advance. We had no idea when we got the news that his dad was sick that we would have to film this scene within days of seeing him for the last time. And we definitely had no idea this episode was going to air on Father's Day. It was a lot.

"I wish people knew what was going on behind the scenes when they see someone's work.

"Anybody who's in this line of work is usually tapping into something hard. The thing he was tapping into was really hard, but also very fresh. Working when you're raw like that is a special skill set."

The couple's children, Gus, 15, and George, seven, joined them on set of TWD: Dead City and Hilarie praised the teenager in particular for the support he offered his dad.

She said: "Our kids were there with us and in his trailer hanging out, so he could just be silly with them in between every take.

"Even when I wrapped, our son stayed with him at work and just shadowed the director and got to hang out with the camera crew. And so the balm that eases loss like that is being surrounded by the people who are still here and that we get to love on. Our son stepping up and being there for his dad at work was also a very cool turn of events."