Philip Seymour Hoffman's partner has revealed she warned him he would die from a heroin overdose.

The iconic actor tragically passed away at the age of 46 in February 2014 when he overdosed on the drug - which he had relapsed into in 2013 after many years of sobriety - and his partner Mimi O'Donnell has now revealed she was ''terrified'' when she discovered he had relapsed, and knew it would end in tragedy.

Mimi - who has Cooper, 14, Tallulah, 11 and Willa, nine, with Philip - said: ''As soon as Phil started using heroin again, I sensed it, terrified. I told him, 'You're going to die. That's what happens with heroin.' Every day was filled with worry. Every night, when he went out, I wondered: Will I see him again?''

The star entered rehab, but struggled with addiction once again when he was filming the third instalment of the 'Hunger Games' franchise in Atlanta.

Mimi admits that she knew something was wrong when he returned home from the set, but within days he had passed away.

She said: ''It happened so quickly. Phil came home from Atlanta, and I called a few people and said that we needed to keep an eye on him. Then he started using again, and three days later he was dead.

''I had been expecting him to die since the day he started using again, but when it finally happened it hit me with brutal force. I wasn't prepared. There was no sense of peace or relief, just ferocious pain and overwhelming loss. The most difficult - the impossible - thing was thinking, 'How do I tell my kids that their dad just died? What are the words?'''

In the almost four years since Philip's passing, Mimi insists she and her children still talk about him ''constantly'', but they are now able to look back on his life with love instead of sadness.

Writing in an essay penned for Vogue magazine, Mimi said: ''It's been almost four years since Phil died, and the kids and I are still in a place where that fact is there every day. We talk about him constantly, only now we can talk about him without instantly crying.

''That's the small difference, the little bit of progress that we've made. We can talk about him in a way that feels as though there's a remembrance of what happened to him, but that also honours him. We talk about his bad sides and his good sides, what he did that was funny and what he did that was crazy, and what he did that was loving and tender and sweet. We open up, and it brings us together and keeps his spirit alive.''