Austin was at West Brom in February 2020 when he got into an online altercation with a few supporters.
He described them as “s***” during the exchange, which he has come to regret.
"Of course I regret it, it left a sour taste in the mouth," Austin told the Daily Echo.
"I'd had a couple of beers. It was more tongue and cheek and then it got way out of hand.
"I enjoyed my time at Saints. They gave me the opportunity to play in the Premier League and the Europa League.
"We got to the League Cup final and lost to Manchester United but there is a black cloud because of a blip on my behalf.
"It kind of snowballed. I look back and think that shouldn't have happened. Of course, it shouldn't have.
"That's why I don't like the fact that when things get spoken about, that's what people mention. It's come from me by the way, I fully hold my hands up there.
"I've made a couple of mistakes in my career. I put in a transfer request when I was first at Swindon, had I been older I would have known it eventually happens.
"Then I had that and I think cor, could I have dealt with that better? 100 per cent."