The tailor, who stars on the ITV2 reality series, told of how he took 40 painkillers in an attempt to end his life, after being accused of cheating on then-girlfriend Lucy Mecklenburgh.
He opened up to Now magazine after an undisclosed "secret" of his was talked about on 'TOWIE', following his split from Lucy.
"I didn't ever want to talk about this because it's not nice. And I didn't want my family or friends to know," he said.
"The only people who know what happened are my mum, my best mate Miller and my manager - but Lucy's been talking about this 'big, dark secret'. It's made people think I've done horrible things to her when I haven't.
"I took an overdose of 40 horrendously strong painkillers that I'd got on holiday earlier this year and washed them down with half a bottle of champagne.
"I fell asleep and woke up at 5am being violently sick. I can't remember much, only that I was relieved when I woke up because I realised how f**king stupid I'd been."
The star revealed that he is now seeking help for his depression from a counsellor, who he sees once a week.
Following his breakup from Lucy, Mario told Digital Spy that he had done "something much worse" than cheat on her.
However, viewers of 'TOWIE' later saw him confess to his mother that he had been unfaithful while they were together.
Lucy is currently suspended from the show, after getting in a catfight with co-star Jasmin Walia.
Read the full interview with Mario in this week's Now magazine, out now.
If you are affected by any of the issues raised, call The Samaritans on 08457 90 90 90