DRUG ABUSE TEARS KHLOE KARDASHIAN AND LAMAR ODOM'S MARRIAGE APART

Khloe Kardashan and Lamar Odom

Hardcore drug abuse is the core reason for the marriage crisis of Khloe Kardashian and Lamar Odom

Multiple sources familiar with the situation say Lamar has had a DRUG problem for 2 years.  It got so bad, last August Khloe pressured Lamar to go to rehabilitation center, and  Lamar obliged, but he was so resistant Khloe had to hire private investigators to secretly stand guard at the rehabilitation center to make sure he didn't leave.

Lamar constantly threatened to leave and Khloe made several visits to prevail upon him to stay.  We're told after 3 weeks, Lamar left for good.

We're told Lamar actually stayed clean once he left rehab and was able to play well for the Clippers this past season.  But when the season was over, sources say Lamar slipped deep back into hardcore recreational drugs. 

As for reports that Lamar was cheating recently, we're told Khloe is convinced it happened, and she feels she's been hit with a double disappointment, but drug abuse is the main problem in the marriage.

As for divorce ... neither Khloe nor Lamar has contacted a lawyer.  As one source put it, "Khloe is more concerned about saving Lamar than ending her marriage."

However, Khloe has kicked Lamar out of the house.

From the above picture, one of Lamar's friends is loading Lamar's stuff in his car as Lamar watches.