The actor, 33, tells W magazine, "There were a good four or five months of not being able to get out of bed. It was the worst time in my life."
But that was then. "You get through it," Phillippe says now. "It's a process that's not easy, but I get less and less sad about it every day."
The marriage produced two children for the couple: Ava, now 8, and Deacon, now 4. The pair's split prompted speculation that acting couples cannot peaceably co-exist – especially when the woman earns more than the man (let alone wins an Oscar). Phillippe acknowledges that theory, but doesn't necessarily buy its premise.
"I certainly understand the level of interest that comes along with a public marriage, and with being married to someone like Reese, who so many people love with good reason. People want answers," he says. "But I think sometimes they wouldn't be happy with what the answers would be."
Complicated ReasonsInstead, he says, the reason for the breakup was "far more complicated and far less interesting than it's made out to be. To look and search for these salacious reasons, to pin it on a person, or a moment in someone's life, it's not realistic."
Though the drama of the divorce has died down – and he and Witherspoon, 31, "have done a really good job at keeping things peaceable and completely focused on" the children – "I spend a lot of time just holed up in my house in Los Angeles," he says. "I don't really go out because I know it's going to turn into a photo shoot."
Though Phillippe is in the new movie Stop-Loss, a drama about Iraq war soldiers, he admits that the main reason he's of interest to the paparazzi "is because I was married to the highest-paid actress in the world. Even though I'm not with her any longer, there is a certain amount of notoriety that I guess sticks beyond."
Say he, "It's just not interesting to me. It's not how I want to be defined."
As for reports that his current costar, Abbie Cornish, was the third wheel in his marriage, and one of the possible causes of the divorce, Phillipe laughs off the notion.
"It was unfair for her to be called the names that she was, because it wasn't about that," he says. "I don't think an outside person can ever cause a divorce. I had difficulties in my relationship, and in my marriage, long before I ever met her."