It will be a "tough and tearful week, even for the daughter of the Iron Lady," Carol Thatcher said on Saturday.
The daughter of Baroness Thatcher made the poignant remark in a statement to reporters outside the family home in London's Belgravia.
She thanked people who had sent messages of sympathy and support, which had given her strength in the days before Wednesday's funeral for the former prime minister at St Paul's Cathedral.
Ms Thatcher, wearing a black shawl, black trousers and clutching a pair of sunglasses, posed for photographers with brother Sir Mark after giving her statement outside the house in Chester Square.
She said: "I would just like to say that I feel like anyone else who has just lost a second parent.
"It's a deeply sad and rather thought-provoking moment in life.
"My mother once said to me: 'Carol, I think my place in history is assured'.
"The magnificent tributes this week, the wonderful words of President Obama, and others of colleagues who once worked alongside her, have proved her right."
She thanked those who had sent her "messages of sympathy and support", adding: "These have given me strength.
"But I know this is going to be a tough and tearful week, even for the daughter of the Iron Lady."
Meanwhile it emerged that Lady Thatcher left instructions that the Prime Minister should give a reading at her funeral.
The former premier laid down detailed instructions as to how the service should proceed, according to The Daily Telegraph.
They were said to include the choice of hymns - among them the patriotic I Vow to Thee, My Country - and readings from the Bible.
She specified that the prime minister at the time of her death should read a lesson from the Gospels.
Her choice of reading was John 14.1, which says: "Let not your heart be troubled: ye believe in God, believe also in me. In my Father's house are many mansions: if it were not so, I would have told you.
"I go to prepare a place for you."
Another lesson will be read by Lady Thatcher's 19-year-old granddaughter Amanda, the Telegraph said.
The service will also include readings from the Book of Common Prayer, including the burial prayer that begins: "Man that is born of a woman hath but a short time to live and is full of misery. He cometh up and is cut down like a flower."
There will be the traditional reading for meeting the body arriving at a church, which begins: "I am the Resurrection and the Life, saith the Lord. He that believeth in me, yea, though he were dead, yet shall he live."
Among the other hymns selected by Lady Thatcher are John Bunyan's To Be a Pilgrim and Love Divine, All Loves Excelling.
It was announced last night that MPs and peers will be able to pay their respects to Lady Thatcher in Parliament's Chapel of St Mary Undercroft on the eve of her funeral.
The chapel will be open on Tuesday evening so members and staff from both Houses can visit the former prime minister's coffin.
Around 100 people will also be invited to a short service led by the Dean of Westminster welcoming Lady Thatcher's body.
Downing Street said Lady Thatcher had requested her body rest overnight in the historic chapel, and the Queen had given her consent.
"There will be a short service for around 100 people, led by the Dean of Westminster, to receive the body of Baroness Thatcher in the chapel," a spokesman said.
The service will not be a public event and will be attended by the family and senior figures from both Houses.
The remaining seats in the chapel will be offered to members and staff who knew or worked closely with Lady Thatcher or who served her in some personal capacity such as housekeepers who looked after her office in the Houses of Parliament.
It is understood Lady Thatcher's body will arrive at the Palace of Westminster by hearse, and leave again by hearse without a formal ceremony.