Howley spoke out as he nears the end of an immediate nine-month ban on any involvement in the sport, which was imposed by the Welsh Rugby Union after he admitted breaching betting regulations.
The 49-year-old’s gambling issues blew up in his face at the worst possible time as a betting company got in touch with the WRU just as Wales were travelling to Japan for last year’s World Cup.
The assistant coach was sent home a week before Wales’ opening match in September last year after it emerged he had placed 363 bets on more than 1,000 rugby matches from November 2015, losing more than £4,000. On two occasions he bet on Wales players to score tries.
After a course of therapy, Howley believes the gambling stemmed from the death of his sister in 2011.
The former British and Irish Lions international told the Mail on Sunday that he had not paid his sister, Karen, his weekly visit in the days before her death and had agonised over his decision to find her a place to live away from their mother as she battled with depression and alcoholism following a divorce.
Howley said: “I blamed myself for her death. If I’d seen her on that Wednesday, would she still be alive?
“There was a lot guilt, should haves, could haves. By putting her in that house, on her own, I created an environment for her to kill herself. Her alcoholism went from bad to worse...... My feeling was that I had driven my sister to her own grave.”
Howley “completely” blocked out the ordeal as he threw himself into his work – he had been on the Wales coaching staff since 2008.
However, the feelings were reawakened in November 2015 when he sorted out his sister’s estate and discovered a number of police and financial issues. He turned to betting.
He said: “It was never about the money. Never. It wasn’t addictive behaviour. It was about escaping. A means of forgetting about the bad things and the experience of my sister.”
After the issue emerged while he was in Japan, Howley described the “humiliating and embarrassing” experience of telling senior players what he had done before leaving Japan and similar feelings of letting down his wife and two daughters.
While he did not want to leave his house for almost three months, he described former Wales head coach Warren Gatland’s support as “unwavering” and revealed a decision to see a clinical psychologist over a three-month period helped him understand why he had gambled and gave him closure over his sister’s death.
Howley, whose ban expires on June 16, now wants to return to rugby and revealed Wasps had “reached out” to him before Christmas about working with Dai Young.
“That phone call from (Wasps owner) Derek Richardson gave me a huge boost, reassuring me that I have a future in the game,” he said.
“Given my experience of the last nine months – some self-reflection and self-awareness – I’d like to think it will benefit me as a coach.”
He added: “I now feel at peace with myself and I’m no longer battling my demons, although there is not a day that goes by without thinking about Karen.”