Former England and Lions number eight Richards will return from a three-year worldwide coaching ban this summer when he starts work as Newcastle rugby director.
He was suspended in 2009 during the fall-out from Harlequins' 6-5 Heineken Cup quarter-final defeat against Leinster at the Twickenham Stoop.
Richards, Quins rugby director at the time, instigated a chain of events that saw wing Tom Williams replaced by goalkicker and potential matchwinner Nick Evans, who had earlier gone off injured.
Blood pouring from Williams' mouth, though, was fake and Richards paid a hefty price, subsequently resigning his position at Quins and then being banned.
"There is huge regret for everything that went on," 48-year-old Richards told BBC Sport.
"I felt very guilty. I put a lot of people in a position where they could have lost everything.
"I'm not the type of person to go match-fixing. I am very competitive, and the reason I did it is because I wanted to win a game. I shouldn't have done it."
Richards now hopes to put the whole unsavoury episode behind him, adding: "I hope I haven't served my three years for nothing. I hope other people have learned from my mistakes.
"I am still as competitive as ever, but I know the boundaries that I have to work in.
"People may think I am a cheat. That's up to them, if they want to. I have no issues if that's the way they feel.
"I know who I am, and I know what I did. I wasn't particularly pleased with myself. I wasn't proud of myself. But you move on and you look forward rather than back."
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