The two-time World Cup winning first five-eighth, who moved to France to play for Racing 92 at the end of 2015, told the the Devlin Radio Show thinking about the February incident made him "feel sick".
"I felt like I let a lot of people down and still feel pretty sick about it," he said.
"It's not about the punishment that the judge gives you or the fine or anything like that, it's actually the potential consequences that really hit home for you. It actually made me feel sick and it makes me feel sick now, thinking and talking about it."
