The couple waited until the whole family could be together before revealing their plan to split, sources tell PEOPLE. "They plan on co-parenting and doing absolutely everything in the best interest of the kids," says a source, adding that the three youngsters are "their top priority."
Despite being privately separated for several months, the couple waited until school was out for the summer before announcing their split on June 30.
"They were together as a family that day," a source tells PEOPLE. "The family felt it was important to be together and they were together. The family is united and, no matter what, will protect the kids. This isn't easy for anyone and it's devastating to Ben too. He loves his family and will always put them first."
Since then, the family has been able to stay under the radar, shielding the young ones during the initial swirl of publicity following their announcement.
In the weeks before their split, Affleck and Garner made sure to spend time together with their children and were often spotted doing activities as a family near their home in L.A., including weekly farmer's market trips and stuffed animal and toy shopping at Brentwood Country Mart to celebrate the end of the school year.
As for the near future, both parents will continue to live together in the family's Pacific Palisades, California, home, as they plan to share custody.
"Ben was a family man when he could be and his kids adore him," says another source. "He traveled a lot but when he is with the kids he's really with them, taking them out for treats, having fun with them. And there is nothing more important to Jen than being a good mom."
The couple's devotion to their kids was also made clear in their divorce statement, "We go forward with love and friendship for one another and a commitment to co-parenting our children whose privacy we ask to be respected during this difficult time."
Reporting by AILI NAHAS and ELIZABETH LEONARD