Khloe Kardashian and Lamar Odom's marriage troubles stem from Lamar's drug use, according to new reports.

The former Laker, 33, has abused OxyContin and Ambien for two years and even went to rehab last August after the Kardashian clan pressured him to seek help, according to RadarOnline.

OxyContin is a prescription painkiller known as "hillbilly heroin" - it's a drug 1 1/2-times stronger than morphine. And Ambien is a sleep aid for insomnia, commonly used by abusers of other substances.

X17 had the same information a month ago — that Lamar had fallen back into old habits and the drug use was ripping their relationship apart. Further, the drugs led to infidelity, a source told X17online, which made matters worse:

    "Khloe felt she was losing her best friend. She knew Lamar could be a great guy and she wanted to save him and get back to that. The problem became that since the cheating, it's been painful and since Lamar hasn't been good about staying clean, Khloe's at the end of her rope."

With these two on the rocks and Khloe removing her wedding ring, the Kardashians are panicking and Kris Jenner's working overtime on some serious damage control. Stay tuned for new pix of the family today ...