Jennifer Garner is remaining ''supportive'' of her ex-husband Ben Affleck, after he admitted to having a relapse in his sobriety.

The 47-year-old actor - who has been open about his battle with alcoholism - was spotted stumbling and falling against a car at a Halloween party over the weekend, and later admitted he had had a ''slip'' in his sobriety journey, just one day after celebrating a year since cutting alcohol out of his life.

And now, his ex-wife Jennifer - with whom he has daughters Violet, 13, and Seraphina, 10, and son Samuel, seven - is said to be sticking by his side, despite feeling ''upset'' about his relapse.

A source told Us Weekly magazine: ''She's upset but always supportive.''

Following the sighting of the 'Justice League' star over the weekend, Ben told reporters he wouldn't let his slip up ''derail'' him from his sobriety journey.

He said: ''Well, you know, it happens.

''It's a slip, but I'm not going to let it derail me.''

The slip-up and his subsequent comment comes just after Ben joked about headlines focused on his private life, and then pledged to donate to homeless charity The Midnight Mission.

He recently wrote on Instagram: ''HA, you got me. I'm dating. But let's be serious for a moment and talk about something that is actually important.

''I have been in recovery for over a year and part of that is helping out others. @themidnightmission is an incredible organisation that helps those in need with housing, training, development and recovery.

''I'm making a donation today because there are people battling addiction every day that don't have the resources and need help. @raya, you in? Who else is with me?''

Meanwhile, the 'Gone Girl' actor has been candid in the past about the ''full-time commitment'' that comes with his ongoing recovery.

He previously wrote: ''Battling any addiction is a lifelong and difficult struggle. Because of that, one is never really in or out of treatment. It is a full-time commitment. I am fighting for myself and my family.

''So many people have reached out on social media and spoken about their own journeys with addiction. To those people, I want to say thank you. Your strength is inspiring and is supporting me in ways I didn't think was possible.

''It helps to know I am not alone. As I've had to remind myself, if you have a problem, getting help is a sign of courage, not weakness or failure.''