The actress worked with Hoffman on a number of films, including Boogie Nights and The Big Lebowski, and they were shooting their latest project, the third installment in The Hunger Games franchise, when he died from a drug overdose in February (14).
Moore, who was among the mourners at his funeral, now admits she is still deeply affected by the loss three months on.
During her trip to the Cannes Film Festival in France, Moore tells Britain's The Guardian, "Let's not talk about this... It was a really horrible thing to happen. It's been so upsetting for all of us. We're all still trying to come to terms with it."