Arg entered rehab over the festive season after being suspended from TOWIE in October due to excessive partying. Arg returned to the show at the beginning of this month.
Joined by co-star Jessica Wright on ITV's This Morning, Arg said during the 28-day programme, Lydia was always by his side.
"Lydia was amazing, she really wanted me to get help and treatment," Arg said. "And whilst I was in there - although we weren't together - she kept coming to visit me and with her love and support she's been amazing.
"For an ex girlfriend, to do as much for me as what she did meant a lot and we've remained good friends which is nice."
Arg said it was the downfall of his relationship with Lydia that made him realise he needed to seek treatment.
"I was reunited with my long term on-off girlfriend Lydia and we got back together, and I lost her due to my wild partying and letting her down and I'd been suspended from the show.
"It almost seemed like everything I'd cared about just didn't seem to matter anymore. I wasn't turning up to filming sometimes, somtimes giving excuses, or I'd turn up late.
Arg continued: "I was letting my friends down like Jess and Mark Wright and I realised that if I don't go in there now, then I'd probably end up losing absolutely everything."
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Watch Arg's transformation below: