EXCLUSIVE: Michael Douglas 'Resented' Drug-Addicted Son at the Height of His Dependence Issues — 'I Didn't Fully Understand Addiction'

Michael Douglas admitted he "resented" his drug-addicted son at the height of his dependence issues, RadarOnline.com has learned.

In his new memoir, One Helluva Ride, the 82-year-old recalls his son, Cameron, struggling with drug dependency from an early age, even sinking himself into legal trouble.

According to Douglas, his son's condition "worsened" after returning to high school following a stint at boarding school. As a teenager, Cameron began mixing cocaine and heroin, which was called "speedballs."

"At the time, even though I had been to rehab myself, I didn’t fully understand addiction," Douglas writes.

He worked to support his son through the drug addiction, but it wasn't easy. He recalled receiving "middle-of-the-night calls" from Cameron, which became routine for the family. However, they only became increasingly "worrying."

Douglas' care only turned darker. "Guilt was replaced by resentment. I could not believe that my son, whom I loved dearly, would keep slamming his head into a brick wall like this over and over," the Oscar winner recalls.

Douglas observed that Cameron's school didn't help facilitate recovery, as returning to high school put him "at a much tougher place with much tougher kids." Cameron "got beat up a few times" in his early days at the school, but Douglas concluded it was "because he was looking for trouble."

"In the process, he became quite tough himself," Douglas writes, recalling Cameron's group of friends the actor didn't approve of.

He notes, "I only knew a fraction of what they got up to and wouldn’t understand the full scope of it until Cameron wrote his own memoir after he was released from prison. One time, he and his friends went to Las Vegas, got in a fight at an amusement park over bumper cars or something, and he was stabbed. Luckily, only in the elbow."

Cameron was first charged with felony possession of a controlled substance in 2007. However, it was only the first of a series of drug-related law violations to come.

In 2010, he pleaded guilty to conspiracy to distribute drugs and heroin possession. His stint in prison came at age 31. He didn't leave prison until he was 37 years old. Cameron has since penned his own memoir, Long Way Home, opening up about addiction.

Douglas believed time behind bars would be best to help curb the behavior. Speaking on The Today Show at the time, Douglas said, "I can't condone his behavior. I think the court recognized his drug addiction as well as the crime that he committed, and it's an adequate, I think, amount of time for anybody to spend in jail. And the best part of it is, he will be able to start his life afresh."

Douglas himself spent a stint in a rehab facility for alcohol and drug addiction, particularly citing cocaine as one of his vices. While drug use was rampant in Hollywood during the glory days of his career, Douglas noticed when his usage rose above the rest.

His now-ex-wife, Diandra Luker, gave him an ultimatum after she found him in a hotel room with another woman. Either Douglas could go to rehab, or they were headed for divorce.

Douglas also shut down a rumor that he went to rehab for s-- addiction, despite his separate confessions of infidelity.