The 46-year-old actress and singer – who celebrated her birthday in May – told MailOnline: “I did have a three-week period in lockdown where everything went out the window.
“I spent a year sober. I didn't have a drink for a year – not because I had a problem with drinking so it wasn't an issue but I stopped drinking for a year.
“But then I massively fell off the wagon and drank and drank and ate all the things I shouldn't.
“By about the third week of doing that I said to Eddie, ‘I need to be good again now.’ I had a brilliant time but I thought I couldn't be doing this.”
The former EastEnders star – who wowed audiences as Fox on The Masked Singer at the start of the year – has been living in lockdown with 10-year-old daughter Betsy and city broker boyfriend Eddie Boxshall, who has two adult children.
Van Outen said the time spent together had made her realise Boxshall is “the one” and that they would like to get married.
She said: “We have got on so well. We have not had one argument or fallout the whole of lockdown. We have really enjoyed each other's company.
“He is definitely The One. If there was ever a test then it's lockdown. We have had a lot of laughs together.”
She added: “About three years ago we did talk about having kids, but I'm 46, Eddie is 47 and I know people do still have babies in their mid-40s but between us we have three kids and we love our lives at the moment.
“But we have talked about getting married. We certainly wouldn't do it at the moment. We wouldn't want a socially distanced wedding. At some point it would be nice.”
Van Outen was married to fellow West End star Mead, 38, from 2009 until 2013. They met when Mead won the BBC TV talent show Any Dream Will Do, which she was a judge for.