Now we’re not trying to start the year with any sort of negativity, but you’re probably going to be crying a lot in January. Fact. A certainty that is entirely dependant on the fact that Beautiful Boy will be hitting cinema screens imminently.

In case you’ve been hidden under a rock (away from Timothée Chalamet’s awards season-ready sequin harness), Beautiful Boy is the heartbreaking true story starring the aforementioned star and Steve Carrell as a family torn apart by addiction.

Based on the inspiring memoirs written by real-life dad David Sheff (played by Carell) and his son, former meth addict Nic Sheff (Chalamet), the film gives us a poignant look at the ups and downs, the struggles, relapses, turning points, anger, forgiveness and unconditional love at the heart of this true story.

Chalamet puts in the blazing performance of his career as you witness the volatility, plus the shocking physical and physiological degradation as the addiction takes hold. And Carrell, is a steady, unmovable rock of support and love, who at one point dredges a city’s backstreets in the desperate search for his son. Expect tears. And we’re talking ugly-crying, lump-in-the-throat tears, from opening scene to credits.

And as well as being an almost certain Oscar contender, the movie is also the English language debut of Belgian film director and screenwriter, Felix Van Groeningen.

We chatted to Groeningen about his certified sobfest, Timothée Chalamet and addiction…

What made you want to tackle Beautiful Boy as your English language directorial debut?
I met the real people David and Nic, and so many things were telling me that I had to do it. I really fell in love with the Sheff family, who were so honest about what their family had been through. And when I read the books, it made me realise that addiction really, really, really is not a choice. And that it was important to make a movie that has that at its centre.

Do you have any experience with addiction?
Not me myself, but family members. I grew up in a bar. I’ve always been pretty close to people who have been addicted, or are suffering with it. What it made me realise when I read the book is that we as a community, or us as a family, or as a person, have the tools to help these people.

Apart from addiction, what else is the film about?
It is about a family that believes in unconditional love, and what it is to be a parent. And what you must go through as a parent. I’ve just become a father myself. I speak from that experience. My children mean the world to me, I want the best for them, I will always be there for them, but you also have to come to terms with the fact that you cannot choose for them to live or die. I could also really relate to Nic, you know. I felt when I read the book that I could relate to where it might have come from. When you grow up, and the world’s too much and you’re struggling…

Can you talk me through the casting process?
I never had the urge for the cast to really physically resemble David and Nic… Steve was really the first person we reached out to. As we were developing the movie, Steve’s name came up and it just seemed perfect for so many reasons. He’s an incredible actor, very relatable to other people, and he is who he is in real life: an honest, sincere person and a very dedicated father.

And what about Timothée?
He wasn’t very well known at the time. We casted the film about a year and 8 months ago. I’d heard of Call Me By Your Name, it just played at Sundance and was getting great reviews, but nobody knew it was going to blow up. But I did see an incredible actor and when he came in and he met with Steve, we had our father and son. They were made to be father and son. They loved each other.

How was the audition process?
The big scenes in the movie were part of the audition. The scene in the diner and the joint smoking scene. Auditioning is like falling in love for me. Especially when you have a lot of people come by. When we saw Timmy it just really made sense. On the other hand, he is this character who can really switch from one moment to the other, where you would see the Nic you fell in love with but at the same time switch to this person, who is strung out and sad.

And how did everyone get into character?
Timmy lost a lot of weight. All the very heavy scenes, where he was really at the end of a bender, those were shot right at the beginning of the movie, after he’d lost like 18 pounds. In the weeks leading up to that we also did makeup tests and he was really becoming that person.

What do you think was the most challenging scene to film?
I guess that scene in the diner. We shot it on day three, which in hindsight is pretty crazy. The actors were so in it. We did these 10-minute takes, 20 times in a row. It took a while for them to be on the right track, and then they were just doing it. What I love about about directing is you never know what the day’s going to be. It’s always sort of improvising. I need to cry. If I’m not crying, we’re not getting there.

You need to be moved to tears when directing?
If I’m not crying, it’s my job to tell the actors how they can make me cry.

What kind of things were you telling them?
Sometimes it’s about approaching it differently. It’s maybe too angry from the beginning. Sometimes you feel it immediately. Does it work? Yes, because I’m crying. I think part of what’s important to being a director is to create a safe room where people feel like they can try anything, and they’re trusted and loved. I’m the biggest fan of my actors and that’s why I look after them.

What has the feedback been like?
It is all a very moving experience. I think the thing that really is important to us, or that makes me proud of the film is a lot of people say it’s a super accurate portrayal. At every screening I have people with experiences telling me the film is giving their addiction a place in their life, or they’re happy that the film was made because they want other people to understand what they went through. I’ve also had feedback from the families of people suffering from addiction, or even from people suffering from addiction themselves. Hearing the feedback, I cried my eyes out, I went home and I hugged my kids harder than ever before.

Beautiful Boy is in the cinemas on 18 January.