This week, everybody has been arguing about rape, and what it means. Following the Assange case, standing in the crowd to hear him deliver his Evita speech from the balcony of the Ecuadorean embassy, debating with men and women online, I've heard a great many people from all parts of the political spectrum tell me that the women who accused the WikiLeaks founder of sexual assault were lying, or they were duped, or they were "honey traps", or, most worryingly and increasingly often, that their definition of rape is inaccurate.

The people saying this are not all prize imbeciles like George Galloway or frothing wingnuts like the Republican Senate candidate Todd Akin. Some of them are just everyday internet idiots who happen to believe that if a man you have previously consented to sex with holds you down and fucks you, that isn't rape. If you were wearing a short skirt and flirting, that isn't rape. If a man penetrates you without a condom while you're asleep, against your will, that isn't rape, not, in Akin's words, "legitimate rape".

Old, white, powerful men know what rape is, much better, it seems, than rape victims. They are lining up to inform us that women – the discussion has centred around women and their lies even though 9 per cent of rape victims are men – do not need "to be asked prior to each insertion". Thanks for that, George, not that it's just you.

There's an army of commentators who also believe "that's not real rape" is both a valid defence of a specific political asylum-seeker and objective truth. Women lie, they say. Women lie about rape, about sexual assault, they do it because they're stupid or wicked or attention-seeking or deluded. The observation that the rate of fraud in rape cases remains as low as the rate of fraud in any other criminal allegation – between 2 and 4 per cent – has no impact. Women lie, and they do it to ruin men in positions of power.

As a culture, we still refuse collectively to accept that most rapes are committed by ordinary men, men who have friends and families, men who may even have done great or admirable things with their lives. We refuse to accept that nice guys rape, and they do it often. Part of the reason we haven't accepted it is that it's a painful thing to contemplate – far easier to keep on believing that only evil men rape, only violent, psychotic men lurking in alleyways with pantomime-villain moustaches and knives, than to consider that rape might be something that ordinary men do. Men who might be our friends or colleagues or people we look up to. We don't want that to be the case. Hell, I don't want that to be the case. So, we all pretend it isn't. Justice, see?

Actually, rape is very common. Ninety thousand people reported rape in the United States in 2008 alone, and it is estimated that over half of rape victims never go to the police, making the true figure close to 200,000. Between 10 and 20 per cent of women have experienced rape or sexual assault. It's so common that – sorry if this hurts to hear – there's a good chance you know somebody who might have raped someone else. And there's more than a small chance he doesn't even think he did anything wrong, that he believes that what he did wasn't rape, couldn't be rape, because, after all, he's not a bad guy.

The man who raped me wasn't a bad guy. He was in his early 30s, a well-liked and well-respected member of a social circle of which I am no longer a part, a fun-loving, chap who was friends with a number of strong women I admired. I was 19. I admired him too.

One night, I went with friends to a big party in a hotel. Afterwards, a few of the older guests, including this man, invited me up to the room they had rented. I knew that some drinking and kissing and groping might happen. I started to feel ill, and asked if it would be alright if I went to sleep in the room – and I felt safe, because other people were still there. I wasn't planning to have sex with this man or with anyone else that night, but if I had been, that wouldn't have made it OK for him to push his penis inside me without a condom or my consent.

The next thing I remember is waking up to find myself being penetrated, and realising that my body wasn't doing what I told it to. Either I was being held down or – more likely – I was too sick to move. I've never been great at drinking, which is why I don't really do it any more, but this feeling was more profound, and to this day I don't know if somebody put something in my drink.

I was horrified at the way his face looked, fucking me, contorted and sweating. My head spun. I couldn't move. I was frightened, but he was already inside me, and I decided it was simplest to turn my face away and let him finish. When he did, I crawled to the corner of the enormous bed and lay there until the sun came up.

In the morning I got up, feeling sick and hurting inside, and took a long shower in the hotel's fancy bathroom. The man who had fucked me without my consent was awake when I came out. He tried to push me down on the bed for oral, but I stood up quickly and put on my dress and shoes. I asked him if he had used a condom. He told me that he "wasn't into latex", and asked if I was on the Pill.

I don't remember thinking "I have just been raped". After all, this guy wasn't behaving in the manner I had learnt to associate with rapists. Rapists are evil people. They're not nice blokes whom everybody respects who simply happen to think it's OK to stick your dick in a teenager who's sleeping in the same bed as you, without a condom. This guy seemed, if anything, confused as to why I was scrabbling for my things and bolting out the door. He even sent me an email a few days later, chiding me for being rude.

When I walked home, it didn't occur to me that I had been raped. The next day, when I told a mutual friend what had happened, the girl who had introduced me to the man in question, I didn't use that word. By that time, I was in some pain between my legs, a different sort of pain, and I was terrified that I had Aids. I had to wait two weeks for test results which showed that the man who raped me had given me a curable infection. I told my friend that I felt dirty and ashamed of myself. She said she was sorry I felt that way. Everybody else in that circle seemed to agree that by going to that hotel room and taking off my dress I had asked for whatever happened next, and so I dropped the issue. Did I go to the police? Did I hell. I thought it was my fault.

My experience was common enough, and it was also years ago. Looking back, being raped wasn't the worst thing that ever happened to me, although the experience of speaking out and not being believed, the experience of feeling so ashamed and alone, stayed with me for a long time, and changed how I relate to other humans. But I got over it. I rarely think about it. For some people, though, experiencing rape is a life-changing trauma.

Yes, even when it's not "legitimate" rape. Being raped by a man who you liked, trusted, even loved – 30 per cent of rape victims are attacked by a boyfriend or husband – is an entirely different experience from being raped by a stranger in an alley, but that doesn't mean it's any less damaging. Particularly not if others imply you are a lying bitch. Sorry if that hurts to hear.

You know what also hurts to hear? People telling you that your experience didn't happen, that you asked for it. That you hate men. That you're against freedom of speech. That's what hundreds of thousands of women all over the world are hearing when they hear respected commentators – not just Galloway or Akin – saying that the allegations made against Julian Assange "aren't really rape".

The idea that fucking a woman in her sleep, without a condom, or holding a woman down and shoving your cock inside her after a previous instance of consensual sex, is just "bad bedroom etiquette" – thanks again, George – the idea that good guys don't rape, that idea has two effects. One: it fosters the fantasy that there's only one kind of rape, and it happens in the proverbial alley with the perennial knife and certainly not to anyone you know. That's what is most disturbing about the discussion going on right now. There are many young men, most of them extremely well-meaning, trying to figure out a way to negotiate boundaries without hurting themselves or others, and those men are being told that sometimes women say things are rape when they aren't really. Two: it makes any man or woman who has ever been raped by a nice guy suspect, yet again, that it's all their fault. It makes rape victims less likely to come forward and report. I didn't report my rape. It took me months even to understand it as rape. I stopped talking about it, because I was sick of being called a liar, and I got the shut-up message fairly fast. I tried to stop thinking about it.

But this week brought it all up again. I'm definitely not the only one who has been revisiting those scenes in my head, playing them over like CCTV footage. I'm probably not the only one, either, who went quietly back to a few friends from the old days to talk about what happened. And what one of those former friends told me was: I wish I'd taken you more seriously, because I think it happened to somebody else.

This isn't about Julian Assange any more. It's becoming an excuse to wrench the definition of rape back to a time when consent was unimportant, just when some of us had begun to speak up, and it's happening right now, and what's worse, what's so, so much worse, is that it's happening in the name of truth and justice, in the name of freedom of speech.

If those principles are to mean anything, this vitriol, this rape-redefining in the name of conscience and whistleblowing and WikiLeaks and Julian Assange – it has to stop. Non-consensual sex is rape, real rape, and good guys do it too, all the time. Sorry if that hurts to hear, but you've heard it now, and there are things that hurt much more, and for longer, and for lifetimes. Those things need to stop.

A longer version of this piece appears at www.penny-red.com