Farrell, 30, spoke for the first time about how he turned his life around after checking into a Los Angeles rehab clinic seven months ago, in an exclusive interview with the Daily Mirror.
"I was burning the candle at both ends and the flames met in the middle," Farrell said. "It just caught up with me. It was a long time coming but I had my ass handed to me on a plate. Now I haven't had a drink for six months."
He also credits his love for his son, James, for giving him the push he needed to sort things out.
"I have a new-found appreciation for my life," he said. "I wasn't suicidal but I never had much of a will to live a long time.
"Now I want to watch my son grow up, be his friend and his father, and hang around with him. So he's the greatest priority in my life."