Demi Lovato’s near-death OD began at 4 AM July 24, when she texted a drug dealer to come to her house … sources tell TMZ.

Sources with direct knowledge say, Demi had been at a party in WeHo following a birthday celebration at Saddle Ranch on the Sunset Strip. After the drug dealer got the text, he came to her house and we’re told the 2 freebased Oxycodone on tin foil.

Word on the street is the drug dealer had a bad habit of buying dirty drugs from Mexico and the batch in question appeared to be laced with fentanyl (that’s the same drug that killed Prince.)

We’re told the dealer left her home when he noticed she was in bed, breathing very heavily. Folks are saying Demi had been using the dealer since April.

You may recall someone on Demi’s staff found her around 11:30 AM on the 24th. She had to be revived with Narcan. Demi was hospitalized for 2 weeks and then went to an out-of-state rehab facility.

Source TMZ