Helmut Kohl is still the "Unification Chancellor" – a giant of contemporary European history who holds an unassailable reputation of having done more than any other post-war German leader to end his nation's division and rid the capital Berlin of its infamous wall.

But as Germany today celebrates the 22nd anniversary of the reunification that Mr Kohl did so much to bring about, the former architect of unity has become a tragic figure.

Confined to a wheelchair because of a bad fall and injuries to his head he suffered four years ago, he cannot speak for more than 10 minutes at a time and when he does, he slurs his words.

The 82-year-old former conservative leader is said to be still fully compos mentis, but he has been prematurely aged by his disability.

To make matters worse, the father of German unity and the ardent advocate of the single currency now stands accused of causing the deepening euro crisis, while his tumultuous private life is likely to be the subject of an upcoming book.

"Reunification is not only one of the underlying causes of the euro crisis, it is also one of the reasons behind our inability to solve it," Wolfgang Münchau, one of Germany's leading economic analysts, said this week. "This is exactly the tragedy of Helmut Kohl: with his great political coup of German unity, he sowed the seeds for the destruction of his greatest political dream of European unity."

Some analysts argue forcibly that Mr Kohl was so blinded by his political obsession with European unity that he pressed ahead with an ill-advised single currency that has plunged the Continent into crisis.

But nowadays it is not only the Unification Chancellor and his euro policies which have become a chief focus of attention. It is rather the neatly dressed, petite 48-year-old woman who never leaves his side. Maike Kohl-Richter has been Mr Kohl's second wife and unofficial carer since the spring of 2008. German media have painted her as a controlling figure, saying she is "building a wall" around Mr Kohl. She is alleged to have terminated close friendships that have endured for decades and is even reported to have been behind a police decision to force Mr Kohl's two sons off the premises of their bungalow home in the west German village of Oggersheim.

"She is looked upon as the Lady Macbeth of Oggersheim," is how Der Spiegel magazine described Ms Kohl-Richter earlier this week. And the heavyweight Sueddeutsche Zeitung, a German national newspaper, said of Ms Kohl-Richter: "There were times when she joined thousands of others to cheer him on. But now she has him for herself, completely herself. They live like two people who have been locked in a museum overnight by mistake. But this is no mistake. This is how she wanted it."

Ms Kohl-Richter grew up in the town of Siegen, near Bonn, and joined the local youth wing of Mr Kohl's conservative Christian Democratic Party. She worked her way up, eventually becoming a government official in the economics department of the Berlin Chancellery in the late 1990s. It was then that she finally managed to meet the man in person.

Mr Kohl's first wife, Hannelore, committed suicide in 2001 after suffering for years from an allergy to light called photodermatitis. In 2005 Mr Kohl announced to the world that Ms Kohl-Richter had become his new companion. In 2008 they were married. But even at this stage it became evident that things had gone seriously awry in the Kohl household. Mr Kohl's two sons, Walter and Peter, with whom the former Chancellor had had an on-and-off relationship for decades, were not invited to the wedding. They were told about it by telegram. "You could feel that my father saw his future with Maike, even if it meant ending his relationship with us," Walter Kohl wrote afterwards.

The German media are convinced that Ms Kohl-Richter is behind the "drawbridge up" mentality that appears to prevail in Oggersheim. The press bases its claim on her alleged treatment of a man who was arguably closer to Mr Kohl than anyone else during the 16 years in which he became Germany's longest-serving Chancellor since Bismarck. Eckhard Seeber, Mr Kohl's former chauffeur, was a combination of personal batman and butler to Mr Kohl for 46 years. "Ecki" folded Mr Kohl's shirts, mowed his lawn and even joined him in the sauna. But when a distressed Mr Seeber went to visit his boss in hospital in 2008, while he was still recovering from his fall, he was confronted by Ms Kohl-Richter in the car park. "Maike told me to park the car in the garage and put the keys in the house. That's what I did and that was the end of it," Mr Seeber told Germany's Bunte magazine. He has not met his former employer since.

Ms Kohl-Richter has so far declined to respond to the criticism. But Hans-Peter Schwarz, a historian who has just completed a new, favourable biography of Mr Kohl, has dismissed the allegations against her as unfair: "It is obviously difficult for her and her husband because of the disabilities Helmut Kohl now suffers from. On certain issues somebody has to decide for him."

And Mr Kohl has told friends that without Ms Kohl-Richter he would probably not be still alive.

But more hurtful allegations could be in the pipeline. One of the figures to have been wounded most is Heribert Schwan, a 67-year-old journalist who spent years ghost writing Mr Kohl's memoirs. Mr Schwan claims he was obliged to sever all contacts with Mr Kohl in 2009.

But now he is planning to respond with a book that may further damage the reputation of Mr Kohl and his wife.

Mr Schwan has 630 hours of recorded interviews with Mr Kohl and intimate details that were revealed to him by his former wife shortly before her death. He has also gained access to the secret police files the East German Stasi kept on him. The book could make interesting reading.

The life of a unifier

Born in 1930, Helmut Kohl was a member of the Nazi Hitler Youth movement but became the first post-war German Chancellor not to have been old enough to serve in the armed forces during the Second World War.

He was a leading figure in regional politics, before entering national politics in the late 1970s. He went on to become the Conservative Party leader and was elected Chancellor in 1982.

He seized the initiative in 1989 by offering Germans the prospect of unity. Intense consultations with the then Soviet leader Mikhail Gorbachev and the leaders of the United States, France and Britain led to a plan being hatched for unification in 1990. Kohl went on to serve two more terms as Chancellor.