I am one of seven women who won an apology from the Metropolitan police in November 2015. We sued them after learning that we had been deceived into having intimate, long-term relationships with men who turned out to be undercover police officers.

The police spied on us because we were involved in environmental and social justice groups. As well as a profound interference with our rights to privacy and family life, their actions denied our rights to freedom of expression and protest – both vital in a society that purports to be open and democratic.

But despite these admissions and apologies, the police have never made any disclosure about what happened, or how and why. In two cases they have refused to confirm the names of our ex-partners, even after we discovered their real identities and provided conclusive proof.

The police claim that in order to protect undercover operations, they can “neither confirm nor deny” (NCND) that our ex-partners were undercover officers, nor confirm anything else about undercover operations. This is despite the fact that they were only too happy to publicise the existence and tactics of the unit my ex-partner worked for in the 2002 TV series True Spies.

Two weeks ago I confronted my ex, John Dines, at Sydney airport. He confirmed his apology in a statement to the Guardian, but I hadn’t gone there seeking an apology. I went because I had discovered that he was now involved in training police officers around the world, including in what is vaguely defined as “leftwing extremism”. I am worried that the abusive and discredited policing tactics used against us and other campaigners might be taught to officers in other countries, putting political campaigners there at risk of the same human rights abuses that we suffered.

In the wake of revelations about deceitful undercover relationships, and about how the police also spied on the grieving family and friends of the murdered teenager Stephen Lawrence, the home secretary announced a public inquiry into undercover policing, to allay public concerns and to prevent such abuses from being repeated.

On Tuesday was the start of probably the most critical hearing before that inquiry gets under way – the decision as to whether or not the police will be permitted to continue to hide behind the shield of NCND and give their evidence in secret, with only the judge able to see documents and listen to witnesses. This lies at the heart of our concerns about this process. For if the police get their way, the victims of these abusive undercover practices and the public who paid for them through their taxes will not be able to see or hear the evidence given. The inquiry will become a meaningless whitewash. If those who suffered at the hands of the police cannot hear the evidence, how can we possibly comment on or challenge it? We won’t even know if we have any relevant evidence to offer. Instead, the police will be able to determine what the judge sees and hears.

I now know the truth about who my ex-partner was, although not how and why he was in my life. But it’s not just me who needs the truth. Many, many more people involved in seeking social change have had their lives spied upon, their human rights abused. They also deserve the truth.

And so does the public. This subterfuge is committed in the name of the public. Taxpayers’ money finances these anti-democratic policing units that seek to undermine and prevent social progress.

We know that special branch spied on the suffragettes and that the Met’s disbanded special demonstration squad spied on the anti-apartheid movement. Both those movements had a critical role in creating a more just and inclusive world. Without interference from undercover policing, that progress might have been achieved sooner.

If the groups spied on remain secret, their members can’t come forward to give evidence about what happened

What is at stake in this inquiry is not just the lives of a few activists, and our understanding about what happened to us, but the future of political policing, both in the UK and around the world. Participants in the public inquiry have called for the cover names of the officers in these political policing units to be released, along with the names of the groups they spied on.

The inquiry is supposed to examine the extent of the abuses committed by these officers, but if the groups spied on remain secret, and their members don’t know they were spied on, they can’t come forward to give evidence about what happened. In those circumstances, the inquiry and the public would never know the true extent of abuses committed and the effect these methods had, both on individuals and on the progressive causes they supported. We need to prevent these abuses happening again. The ability to look behind the NCND strategy will be central to that – it is a wall that must be breached so the truth about this scandal can be heard.