The story of the director of public prosecutions apologising to a sexual assault victim because her case had been handled incompetently is appalling. Such a thing should not be happening today. And I feel particularly strongly about this because I was a juror on the case.

In March last year in a south London court I was selected as one of the 12 to hear a sexual assault trial. The hearing began with the alleged victim recalling how she was out celebrating a birthday in a pub, with friends – and how a couple of them, including her boyfriend, left for home along with another man they'd got chatting to. She'd had plenty to drink and she'd taken some soft drugs. But after falling asleep in her bedroom she woke up to find a man trying to force himself on her.

We were told that the alleged attacker's defence was that he'd never met her – that it was a case of mistaken identity. She said she knew it was him because he was a well-known character in the area, and was widely known to dress in a particular way.

At this point doubts started to enter my mind about how the case was being presented. (I can't speak for other jurors – and anyway it's a criminal offence to reveal jury deliberations.) We'd been told that the alleged victim was the only witness who'd be called. Which was bizarre, given that there were two or three other people who would surely have been able to identify whether the defendant really was the man they'd walked home with. If it was her word against his, and she'd admitted to taking drink and drugs, immediately that would have lodged significant doubt in our minds. And although the victim had since split up from her boyfriend, surely the prosecution should have been able to call at least one other witness. If not, how could we possibly convict if we couldn't be certain he was even present?

Then the case took another twist: when the victim was asked why she had not brought the case earlier (it was now three years since the night in question) she replied that she'd been scared to make the assault claim because he knew where she lived. She added that she only felt safe to report the attack when she'd heard he was in prison. At this point the judge and barristers went into a huddle, and we were told to ignore that last remark. I realised this was a serious development: surprisingly, though, the case continued until the end of the afternoon.

The following morning we were called back into the courtroom to be told that the prison comment meant the judge would have to discharge us. But we were also told that the prosecution had decided to drop the charges.

Even at the time I was shocked that a case involving such serious charges could be handled so badly. It felt as if the efforts to gather evidence were completely slapdash. I knew of the pitifully low conviction rates for rape, and I remember thinking that if this is how they are all prosecuted, I could fully understand why.

Hearing now that the victim felt "bullied and railroaded" by the barristers and the investigating detective into giving evidence without adequate preparation; that she'd expected to be shielded from her alleged attacker while in the witness box; and how she'd been "put through hell" when they dropped the case – without consulting her – the whole thing seems even more deplorable. "The Crown Prosecution Service allowed me, a vulnerable witness, to be crucified in open court in front of my assailant," she said. "The psychological and emotional damage was catastrophic: I slipped into major depression and felt suicidal."

A huge amount has been written about the handling of rape allegations, and the need to improve the methods of evidence-gathering and prosecution, so cases like this simply shouldn't happen. Even more disturbing, specialist prosecutors – supposed experts in the field – were used on the case. And after last week's disclosure that an inquiry into police handling of rape cases has been shelved as part of the coalition government's cuts, it seems the outcome will now be more incompetence, more women victims being humiliated in court, and more rapists going free.

Keir Starmer, the director of public prosecutions, has apologised: "I am extremely disappointed with the way in which this case was dealt with and I am very sorry for the distress these failings have caused the complainant," he said.

The victim feels that, after initially being blamed by the prosecutors for the collapse of the case, she has at last been vindicated and can rebuild her life. And Starmer will now surely have to rethink his entire strategy.