More than a year after his tragic death, Michelle Williams finally talks about losing Heath Ledger.

"I didn't know what my boundaries were for a long time, which made interviews feel very unsafe," Williams, 29, says in Vogue's October issue (on newsstands now) about her former boyfriend, who died of an accidental drug overdose at the age of 28 in January 2008.

She says:

"I can talk about grief because that's mine, about single parenting, about trying to balance work and kids. But what I don't have to talk about is what happened between Heath and me in our relationship."

Michelle met Ledger on the set of Brokeback Mountain.  They dated for three years before they split in 2007.  The couple had daughter, Matilda Rose who is now 3.

She says that when Heath died, she struggled to cope with his loss.

"I was holding it together by a string and a paper clip in the fall and winter," she says. "I didn't know if I could keep it all together... You console yourself by saying it's all a deepening process. But it's wired. After the first year, the pain is less intense -- it's less immediate. But the magical thinking goes away too. And that's a whole new reckoning."

Still, their child provided her strength. 

"Every time I really miss him and wonder where he's gone, I just look at her," she says. 

She started dating Spike Jonze in late 2008 and says it hasn't been easy but feels hopeful and grateful for the future.