Three months after his split from Reese Witherspoon, Ryan Phillippe says, "This is the most difficult time in my life."

"I must stay focused on my kids," Phillippe, 32, tells TV's Extra in an interview airing this week.

Witherspoon filed for divorce on Nov. 8, citing irreconcilable differences. The couple were married for seven years and have two children: Ava, 7, and Deacon, 3.

Asked if he's distracted himself with his work during this tough time, the Flags of Our Fathers star answers: "I have not found balance in my life yet."

Going through a break-up in the public eye makes things harder, he says: "It's unfortunate when you have kids ... but I signed up for this and have to deal with it. I don't read the magazines or watch the shows. ... It's hard when people follow me to my kid's school."

In his first public words about the split, Phillippe told PEOPLE in November: "I'm not a perfect person, but I'm not guilty of a lot of the things I have been accused of. My priority is and always has been the health and safety of my family."

Phillippe would not comment on reports that a relationship with Abbie Cornish – the Australian actress who costars with him in an upcoming film – played a role in the demise of his marriage. But his reps vehemently denied other allegations of hard partying and drug use.