OSCAR winner Renee Zellweger has fallen for a former heroin addict!

But sources say teetotaler Renee, 43, is helping to keep her music man beau, bluesy rocker Doyle Bramhall II, on the straight and narrow.

The “Bridget Jones’s Diary” cutie – who’s divorced from country star Kenny Chesney and was last linked to “The Hangover” hunk Bradley Cooper – was snapped smooching guitarist/producer Doyle, 44, at LAX on Dec. 12.

“Reneeis the best thing that could have happened to Doyle,” said an insider.

“He was brought up playing music on the

 “When he was in his 20s, Doyle had a terrible heroin addiction, but he managed to kick it. Being with Renee helps keep him clean and sober!”

After detoxing in a California rehabilitation facility at age 25, Bramhall said that he hardly rec­ognizes the person he was while addicted to heroin.

“I’ll never know that person again,” he insisted.

“I’ve changed dramatically since that period. During the time that I was doing it, I was going through changes, getting to the point where I was so fed up with it all that I had to stop. It was just insane. But it did end. Which I’m very happy about.

“But I don’t wake up every day and think about it.”

Renee – a Best Supporting Ac­tress Oscar winner for the 2003 drama “Cold Mountain” – and Doyle first met when she was a student at the University of Texas at Austin, said the source. But the two didn’t fall in love until recently.

“Doyle was dating Sheryl Crow last year, and they hooked up after he split with Sheryl and Renee’s relationship with Bradley ended,” said the source.

Things are going well, but there’s no marriage talk just yet, said the source, who added: “Renee’s been gun-shy about another trip down the aisle ever since her marriage to Kenny ended after just four months.”