Michelle Williams has spoken out about how she is coping with grief following her former partner Heath Ledger's death three years ago.

Heath died of an accidental overdose of prescription drugs in January 2008, aged 28. He and Michelle had split up several months beforehand, after dating for three years.

Michelle, 31, admitted she still has sad days but said she had "no choice" but to move forward for the sake of her and Heath's six-year-old daughter, Matilda.

"I feel like everybody gets a mixed bag. There's great stuff and there's horrible stuff. It's just that a lot of people know what's in my bag," Michelle told Elle magazine. "And I can't say that I'm not sad, I can't say that those things aren't true and people aren't making those correct correlations to events and actuality, but I try - because I have no choice, because I have a child - to make something out of it. To make something out of us. To literally remake it.

"Yes, I am sad. I'm sad as often as I'm happy. And so is everybody that I know."

The actress said she was making an effort to put her past behind her.

"I went to see this guru and I got to the beginning of the line and she said, 'Your past is behind you,' and it was a huge revelation. It's behind me. It's not all around me any more. It's not all I can see any more.

"And I have to put it behind me even though I don't want to. And some days I wilfully choose not to, but I have to put it behind me if I want to move forward."

Michelle also talked about her trademark pixie haircut, saying, "I cut it for the one straight man who has ever liked short hair and I wear it in memorial of somebody who really loved it."

Michelle plays Marilyn Monroe in new movie My Week With Marilyn, in a role which has already won her critical acclaim. Watch the trailer for the film here.

Michelle Williams: I am moving forward with my life