The time has come! Jennifer Garner couldn't watch her estranged hubby and the father of her three kids continue his downward spiral so she took matters into her own hands this afternoon and staged an intervention at the actor's Pacific Palisades home just moments ago.

Jen's on PCH, presumably taking Ben back to one of his old haunts like Promises or Passages rehab in Malibu -- two that are super-luxe and favored by celebs.

Our photographer on the scene tells us, "Ben was a mess; he was talking but you couldn't understand what he was saying. Jen was just serious. She looked like she was holding back tears, but at the same time she looked upset. Seems like it's not the first time she's had to do this."

Jen showed up at Ben's home this afternoon at 4pm with a woman believed to be her attorney; she left after about an hour and returned about 30 minutes later (don't forget, she lives with the kids just up the street). When she came back, it was all business. She reversed the car into the driveway and whisked Ben into the back seat. He was sweaty, puffy, looking quite out of it. Jen rested her chin on her hand as she drove and just looked ahead ... with her goal of rehab in mind ... and didn't let Ben distract her.

As Jen left the house the first time, we asked her if it was a good thing that Ben broke up with Lindsay Shookus ... she what Jen said -- you might not expect her answer ...