Jennifer Garner & Ben Affleck Divorce — How Matt Damon Came Between Them

As Ben Affleck deals with his divorce from Jennifer Garner, RadarOnline.com has learned he’s already got an A-list shoulder to cry on — Matt Damon!

Longtime friend Damon, along with Affleck’s agent Patrick Whitesell, "has been helping him through this trying time," an insider told RadarOnline.com.

"They’ve all been best buds since their collaboration on Good Will Hunting," the source explained, "and Ben and Matt have been dedicated to Patrick since they took home their Oscars."

As his marriage crumbled, the source said, his boys were by his side. "They’re sad this is happening, and it’s made them all strategize ways to work on marriages," the source explained.

But Garner, 43, became jealous of the boys-only sessions, according to the insider. "She felt left out and alone, so she started to control things," the source claimed. "It got nasty. She started making thinly veiled threats" to make Affleck, 42, "look bad."

"She knew he was talking to his agent and Matt about their marriage, and she started to feel like she was being ganged up on by the boys," said the source.

Ultimately, as RadarOnline.com reported, they made the decision to announce their divorce on June 30.

Story developing.