AceShowbiz -

After months of keeping mum, Hilary Swank comes clean about her divorce from husband of nearly nine years, Chad Lowe. The actress tells all to Vanity Fair that Lowe's "substance-abuse" problem played an important role in their abrupt separation.

"I knew something was happening but I didn't know what. When I found out, it was such a shock because I never thought he'd keep something from me. And yet, on another level, it was a confirmation of something I was feeling that was keeping us from being completely solid," Hilary says to the magazine.

Also the actress added "I don't want to make it seem like that's the sole reason; there were other factors. But that just kind of blew it open. It made me look at things a lot deeper. That's when you realize it's not going to work." In fact, "He's sober now," said the star. "When I found out, I wanted to be there. I knew it was the most important time of his life. That's when he needed me the most. It's an enormous obstacle to overcome, and he's doing it. He's living a sober life. I know how difficult it is, and I'm really proud of his sobriety."

So, what are you waiting for, get Hilary Swank's divorce confessional in the August issue of Vanity Fair which is set to hit the newsstands Wednesday.