|'Glee' star Lea Michele|
A source told UsMagazine.com: "Lea is trying to talk to the people who last saw him. She wants to know what happened, she wants to understand."
The 26-year-old actress, who was in Mexico when she heard the tragic news, supported Cory, 31, when he entered rehab earlier this year to seek treatment for his addiction to drugs for the second time and believed he was strong enough to fully recover.
The insider added: "Lea long knew about Cory's drug problems and was always pushing him to get help, [as] she believed he'd be unstoppable if he could beat his demons."
The brunette beauty's other co-stars are giving her space to grieve and she "hasn't been in communication with a lot of people" since Cory's death.
The source said she is "only talking to a few confidents", adding she "is in no state to be seen in public."
The couple, who dated for 14 months, were previously said to be planning to move in together after Cory got back from his trip to Vancouver.