Justine Miliband has spoken of her fears that husband Ed will be subjected to "really vicious" attacks during the general election campaign.
Speaking to the BBC, Mrs Miliband said she expects the attacks on her husband to get worse as the May 7 polling day gets nearer, but insisted: "I'm totally up for this fight."
Mr Miliband has been widely mocked by political opponents, the media and websites over his nasal voice, his supposed resemblance to animated film star Wallace and his inelegant consumption of a bacon sandwich.
Asked how she deals with personal attacks of this sort, Mrs Miliband said: "I think it's going to get worse, I think over the next couple of months it's going to get really vicious, really personal, but I'm totally up for this fight."
She added that "the reason is because I think this goes way beyond Ed as an individual, I think it's about whether decencies and principle count for something in political life".
Mrs Miliband revealed that her husband's biggest regret about taking the Labour leadership was "not seeing the children enough or worrying he doesn't see the children as much as he'd like".
She said that they explained his work to children Daniel, five, and Samuel, four, by saying that he leads "the red team".
"There's quite a lot of chats about what the red team's doing and who the red team's helping," she said.
Barrister Mrs Miliband has kept largely out of the limelight since her husband won Labour's top job in 2010, but hit the headlines with a speech at the party's annual conference in 2013 when she insisted she was "more than a dress".
She told the BBC: "The only reason I first gave a speech to Labour Party members at Labour Party conference was because I was so worried that by about three years in, all they knew about me was a dress I wore to Ed's speech and I thought I really want to reassure people that I am, in fact, more than a dress."
Mrs Miliband told the BBC that she was concerned about the impact of personal attacks on politicians "wherever (they) are on the political spectrum".
She said: "It's not just about Ed, it's about every single politician who tries to do the right thing despite the personal attacks.
"I think it's incredibly important that political life in this country stays open to decent principled people.
"If you ask me why I'm up for a fight, I'm fighting not only for Ed but I'm fighting for the principle of decency in public life."
Mrs Miliband admitted she had not yet started thinking about how her life will change if her husband becomes Prime Minister in two months' time.
"I haven't thought about the future particularly," she said. "Probably like most women, being a working mother and having a husband who's Ed, I'm definitely on a 48-hour timetable, so I haven't really thought about it."
Mrs Miliband said her husband showed he had "guts" when he decided to take on Rupert Murdoch and News International over phone-hacking in 2011, though she admitted she was "nervy" about it at the time.
Asked if she ever advised Mr Miliband on policy, she said: "We are married, so we talk about things that happen to crop up.
"One of the clearest examples that has stayed with me is when we were going to work one morning in the car and the radio came on with the news and the news had just broken about phone hacking and about how low some journalists had gone in pursuit of the news.
"We just were totally shocked - that immediate human reaction - and sickened actually. We talked about it and quite quickly, for someone like Ed, it becomes a question not just of that immediate reaction but 'What am I going to do about this?'
"We talked briefly. It was back in 2011 and you didn't take on News International in 2011, so it felt pretty serious. I remember being on the Tube on the way home and I had a copy of the Evening Standard and my eyes caught the headline, which was something like 'Miliband calls on Murdoch to resign'.
"I remember thinking 'He has gone ahead and done that' and that felt pretty nervy and I remember not being quite sure how it would all play out, but I thought 'You have shown you have got the guts to do things that people wouldn't expect'."
Mr Miliband insisted he did not care what people said about him.
He added: "You know what I think people underestimate about me? That I'm much more resilient than they thought.
"People have underestimated me in the past, let's see what the result of this election is."