She talks of their love, her grief and how she censored the media so he would not read bad news about his beloved ANC

As Nelson Mandela's coffin was slowly lowered into the ground in the hills close to where he grew up, his widow, Graça Machel,crumpled with grief. There would, as is customary, be six more months of mourning. But on Friday, Machel broke her silence to describe the pain of losing her "soul mate" and "best friend".

In her first interview since Mandela's death last December at the age of 95, Machel spoke of his "peaceful" last moments and expressed gratitude to the world for its outpouring of support. She also revealed how in recent years she censored his TV and newspaper reading to protect South Africa's first black president from bad news that could have led to disillusionment with the direction of his beloved African National Congress (ANC).

"If you can imagine how millions of people felt this sense of loss, then you can imagine what it means for me," Machel, 68, told the Guardian. "That huge presence, filling every detail of my life, every detail of my life full of him. And now, it's pain, it's emptiness and it's actually searching now – at a certain point you even search yourself, who I am now after this experience. It's like something has changed inside you as well. Of course, you don't go through this kind of experience and you remain exactly the same.

"So when I say I'm searching who I am, it's that kind of reconnection with the person I was before, the person who went through that experience which is fulfilling, but also it is now painful. And now to reconnect and say what next, what am I going to do, how am I going to be part of the thousands of millions of people who are trying to work for a better world. I'm still in that process, actually. The grieving for him is still going to be with us for I don't know how long."

Machel looked composed as she spoke in a book-lined room at Johannesburg's Saxon Hotel, a luxury oasis where 20 years ago the anti-apartheid hero sought sanctuary to finish his autobiography, Long Walk to Freedom. Speaking of Mandela, she slipped between the past and present tense. The official mourning period now over, she will throw herself back into frontline activism on Monday at the Partnership for Maternal, Newborn and Child Health Partners' Forum. Children's health was a cause close to Mandela's heart. Asked if he was pained by media reports of violence against children in South Africa, Machel replied: "Let me be honest with you. From certain years to now, I protected Madiba [his clan name] against that. I didn't want him to be aware of all the things which were happening because, knowing him, he would be really aggrieved, he would suffer, but he wouldn't be able to do much.

"So why, after he has given so much, why? When there were things which were really outrageous in newspapers like babies being raped, etcetera, etcetera, I would find a way to remove the newspapers from him."

The biggest disaster since Mandela's retirement after one presidential term in 1999 was the police massacre of 34 striking mineworkers in 2012, the subject of an continuing commission of inquiry. Machel reflected: "We were already in a period where he would be well and unwell. He did see, he was aware that it was happening but not in its depth, and again I want to take the blame and whoever wants to castigate me for that, because I didn't want him to get into that purpose, no.

"Sometimes it would be three newspapers we'd remove, sometimes it was TV; I would screen the news to know what I should let him see this and not see that, because I just felt it was time for us to protect him and to give him peace."

Machel noted that the ANC "changed him" and "made him" and he was forever loyal to the party. Asked if he lost faith in its current leaders, she answered: "That's what I'm trying to say: we protected him. At a certain point Madiba was not aware of things, not because he wouldn't want to, but because we didn't want him to be engaged so it doesn't disturb him unnecessarily because at that time he wouldn't be able to engage."

Last year president Jacob Zuma and other ANC leaders were criticised for visiting a palpably ailing Mandela and posing for the cameras. Machel reflected: "The moment was not right, and because those who have seen the pictures, it was clear he was not communicating with them. So it was not right to expose him to that kind of a situation."

Mandela's second marriage to Winnie Madikizela-Mandela did not survive his 27-year incarceration during the struggle against apartheid. Soon after, the lonely president began to woo Machel, a former education minister in Mozambique, and even enlisted the support of archbishop Desmond Tutu. They married on his 80th birthday in 1998; she was 27 years his junior.

The last few years of his life saw increasingly frequent hospitalisations and attendant media frenzies. Maintaining a constant vigil, she appreciated the public goodwill. "Very few people living in the world will have been showered with so much love, like Madiba. We experienced that outpouring of solidarity and love and support while he was still sick, and that has helped us to carry on and to feel that no matter how he could be unwell, the world was holding him up in its hands.

"It was really very comforting. Madiba was being informed, I want people to know. As much as I could, I would inform him of letters, of SMSs, and when people would come outside our house and they would leave those messages in stones, I would make sure that at least part of it I'd tell him about. So he felt connected, he felt still part of the world during that period while he was still sick."

Close friends said Machel and Mandela's previous wife Winnie Madikizela-Mandela were both at his bedside when he died. Machel declined to elaborate, saying only: "It was peaceful, yes, definitely. It was peaceful, and that's all I am prepared to share."

"Because Madiba was sick for a long time, his passing was not a surprise, but believe me, there's no such thing as saying I saw it coming. No. When the moment comes, it's there and you start the journey absolutely as one, two, three, five minutes until you get the days. There's nothing which prepares you even if you know your beloved one is sick. Nothing prepares you for the pain of seeing him passing."

Not even being widowed once before: her first husband, Mozambican president Samora Machel, died in a plane crash in suspicious circumstances in 1986. She is the only person in the world to have been first lady of two countries. "If someone believes in destiny, it's the destiny of my life that I was loved and I loved two extraordinary human beings.

"It's different experiences. Every single person is different, so there's no way I can say, 'Oh, I've gone through this. I knew already'. Every experience is unique and you go through it the moment in circumstances and feelings which are new and fresh for that specific moment. There's no thing of saying, 'I knew it already'."

This time Machel drew strength from the legions of South Africans who gathered and sang songs and lit candles outside the couple's home in Johannesburg. "There are things which I couldn't witness because I was so overwhelmed with my sense of loss, the magnitude of loss.

"But I know from what I have been told that from all over the world, actually every TV station, every newspaper talked about him, mostly celebrating his life. If Madiba would have been there, and knowing who he is, he would have said thank you to all those who showered him with love, and because he can't say it, I want to say it on his behalf.

"Having this double feeling: the loss and the pain, but at the same time the warmth of people to sustain us. So please, through your newspaper, say on my behalf, on behalf of our family, thank you. We don't take anything for granted. We know it took a decision and it took feelings to express the way people did."

Machel declined to comment on recent claims that Mandela's relatives tried to freeze her out of his memorial service arrangements. She says she is grateful to the Mandela family for ending the mourning period at six months so she can return to work, starting with next week's global summit on maternal and child mortality in Johannesburg.

Of the five continents of the world, Machel notes, Africa is the one that will not meet the millennium development goals in child and maternal mortality. "Attitudes have to change, institutions have to be sharpened, resources have to increase, and changing this thing of 'business as usual' because the attitude of 'business as usual' is the one which led us in these last 15 years not to achieve much."

Such progress, and a planned children's hospital, which she describes as Mandela's "last wish". Only once during Friday's interview did emotions threaten to overcome her: "Ever since you have seen me with Madiba, we always walked hand in hand. There hasn't been any moment where we were together we wouldn't hold each other's hand. That was the best of moments. Whether it was in privacy, whether it was publicly, it was that kind of connection of communication which we had together.

"I don't want to go into details but I just want the world to remember this is a man with whom, at least for 12 years before he fell sick, I walked hand in hand. Second, when we were relaxed, whether it's in public or whatever, there was always a broad smile on his face. And that's the comforting thing that we were there together. We shared so many moments of laughter and that human connection was very special, and to be honest that's what I miss now. This is what I miss."