Natasha Richardson passed away in March (09) after suffering a traumatic brain injury in a skiing accident in Canada, and the tragedy left her younger sibling Joely heartbroken and "shattered".
And the 44 year old admits she still thinks about her beloved Natasha every day.
She tells Tatler magazine, "We were such opposites, but completely enmeshed in each other... I hadn't lived a day in my life without her. You worry about your children and your elders, but I never imagined such a thing as this. Tash was a given to me.
"So much of what I am is who Tasha was, and I think, sharing all those formative years, there is level of merging... I cannot imagine that there will ever be a day when I don't think of Tasha."
Fans were shocked when Joely returned to the set of TV movie The Day of the Triffids a day after her sister's funeral - but she maintains she needed to work to recover from her loss.
She explains, "The shock shatters you on a cellular level, and it takes time for the pieces to come back together, albeit in a different formation... A strange autopilot kicks in; your psyche puts your work day into a different compartment from your private life. I'm not kidding - my first shot back on set was reacting to someone dying."