On Heather Mills McCartney's official website, Sir Paul lambasted a recent claim in The Sunday Times magazine that "losing her leg was perhaps the best thing that ever happened to Heather as it fed her desire for self publicity".
Lady McCartney had her left leg severed below the knee after being struck by a vehicle in 1993. She also suffered a crushed pelvis, broken ribs and a punctured lung in the horrific accident.
But since meeting and falling in love with Sir Paul six years later, she has been accused of controlling his life and coming between the 62- year-old singer and his children by his first wife, Linda.
In an extraordinary 800-word swipe at their critics, this weekend Sir Paul declares his love for his wife, claims that they make decisions together, and expresses his shock at the most recent media allegations.
"Imagine losing a leg, and dealing with it as bravely as Heather has done and having to read that on top of it," says Sir Paul, adding: "Scurrilous writers can't be bothered to search for the truth of situations like these."
The most recent article enraged Lady McCartney's friends and family who have seen her fight back from horrific injuries. Sir Paul, though, voiced his anger at the general portrayal of his wife.
"There are so many misapprehensions that are spread by certain sections of the media that it is impossible to answer them all.
"I only hope that these words of mine help genuine people to get a clearer view of the realities of our lives."
He claimed that accusations that his second wife had come between him and his children were untrue. "The media sometimes suggests a rift between my kids and Heather, but in fact we get on great and anyone who knows our family can see this for themselves."
Sir Paul married Heather Mills in 2002, four years after his first wife Linda died of breast cancer. It has been claimed in newspapers that Sir Paul's new wife dominates the relationship, making all the decisions about public appearances and charity appeals.
In his web posting, though, the former Beatle refuted allegations that she persuaded him to have plastic surgery ("I haven't had any done"), appear on a charity game show and have his hair dyed.
"It's my hair, and if you don't like the result I'm afraid it's just too bad, but it's certainly nothing Heather suggested. I was engaged in this devilish practice years before I met her."
Sir Paul added that they appeared close in public because they were in love. "She was reported to always be clinging to me, the inference being that she was too possessive," adds Sir Paul in his web posting.
"Never mind the fact that I love her holding my arm, the real truth is that often the surface of a floor or pavement can be dangerous for an amputee to walk on, and a little help from a friend can sometimes be appreciated."
However, media and publicity expert Max Clifford yesterday warned that the decision to go on the offensive could backfire on the McCartneys.
"I don't think this is a good way of dealing with things," said Mr Clifford. "Heather has proved unpopular with the press and Paul is not doing her any favours here."
"If anything, this could lead to more of the same types of articles as the press looks to justify its position. I suspect this will make a bad situation worse for them."