Michelle Williams worries she won't find love like she had with Heath Ledger.

The 'Blue Valentine'actress - who has a five-year-old daughter Matilda with the late actor - thinks it is hard to embark on a new romance because she felt so "whole" with her former fiance, who she was in a relationship with for two years until September 2007.

She said: "That's the tough one. It's like nothing will ever be that whole again. You just want impossible things. I've had to get down on my hands and knees and sift through the muck and mud, and try to find little pearls, little nuggets of things that make sense."

The 30-year-old actress - who dated 41-year-old director Spike Jonze for over a year until September 2009 - feels love is always with her, and though she would like to be dating, she insists she is comfortable being single.

She said in an interview with The Times newspaper: "When you've had love, you always, in a way, have it.

"I am single but either is fine with me. I'm used to being single. Would I like to be with someone? Yes I would."

Michelle sought solace in her work following the death of Heath, who passed away from an accidental prescription drugs overdose aged 28 in January 2008.

She explained: "I feel like I've always had work, that's been the place I can go, sometimes physically just to get out of the house and also emotionally."