Khloe Kardashian to Lamar Odom: You're Not Welcome Here

Khloe Kardashian has given Lamar Odom an ultimatum -- get help or get an apartment.

Our well-placed sources say Khloe has laid down the law -- Lamar can't live at home until he completes rehab -- which he's been unwilling to do since his addiction spun out of control.

Khloe has kicked Lamar out before, but we're told this time she's vowing not to fold ... and Friday's DUI bust was the last straw. Our sources say Lamar didn't call Khloe or his lawyers after the arrest. They found out when TMZ broke the story hours later. Khloe was pissed.

Khloe and Lamar did spend time together Saturday at their home -- but Lamar was sent on his merry way after 4 hours of jawboning about his addiction to crack and other drugs.