Mark J. Terrill/Reuters/Landov
07/16/2009 at 06:20 PM EDT
By all accounts, Jackson matriarch Katherine Jackson has been the rock for family members – including Michael's three children – in the weeks since the King of Pop's death. Now, it's her turn to grieve.
"It's finally hit her," says a source close to the family. "She's been crying a lot. Her eyes are constantly red. She can't believe Michael is gone."
While Prince Michael I, 12, Paris, 11, and Prince Michael II (Blanket), 7, remain surrounded by cousins at the Jackson family home in Encino – having summer fun that includes swimming and water balloon fights – Katherine is struggling to hide her sorrow, says the source.
"She feels horrible for those children," the source says of Katherine, who was named in Michael's will as their guardian and was awarded temporary custody pending a hearing scheduled for July 20. "[But] she's determined to remain strong for them."
The source says Katherine is fiercely protective of all her family.
"She is very upset about all the Joe bashing and all the things that are being said about him," says the source. "Michael's kids love Grandpa Joe. Hearing him trashed makes Katherine really angry."