Clarke Carlisle has admitted that he directed homophobic abuse at his former Burnley teammate Wade Elliott.
From between 2007 and 2011, Carlisle by his own admission taunted Elliott, who is straight, at Turf Moor.
Since his retirement from football, Carlisle has worked within the Professional Footballers' Association and has become an ambassador for anti-discrimination group Kick It Out.
In an interview with GQ magazine, the 35-year-old admitted that he feels sickened by his previous behaviour towards Elliott, who now plays for Bristol City.
"My stomach is turning as I say it, but [I gave him] homophobic abuse, because he is small and people thought he looked a bit effeminate maybe," said Carlisle.
"I have the PFA to thank for making me see how wrong that was. [Football] is also a very homoerotic environment - everyone slapping backsides, but when homophobic abuse is targeted at one individual, it is horrendous - calling him gay when he wasn't. My stomach is really churning now."
Carlisle tried to commit suicide by jumping in front of a lorry on the A64 in Yorkshire last December.