An ex-cabinet minister has spoken out for the first time about how Jo Cox’s murder sent him spiralling into an “abyss” that finally forced him to confront a “buried” childhood growing up with an alcoholic father.

Liam Byrne told HuffPost UK’s Commons People podcast the 2016 murder of his Labour MP colleague triggered “a very deep and dark slide into what I felt was quite a dangerous place”.

During childhood he said he erected “six inch armour plating” around himself because alcoholism was a “big dirty secret” and his family had built up co-dependences that made talking about it difficult.

He described how from the age of seven, as the oldest son, he ended up supporting his mum who was “freaking out” about his father’s drinking, describing it as “often a bit of a violent home” with “a lot of stress and antagonism”.

It was her death on Boxing Day 1997 that sent his father’s to slide into alcoholism because they were “so in love” and had “saved each other from difficult childhoods”.

But he said decades of suppressing his feelings meant he always felt like a “two dimensional person”, even when flying high in the last Labour government in a career that culminated in serving as Gordon Brown’s chief secretary to the Treasury.

Cox’s murder, a year after his father finally lost his battle against alcoholism and “slipped away”, finally flicked a switch.

“It knocked me over really, it was only after he died that I had the space to come to terms with what had happened.”

He then embarked on 18 months counselling “to try and put my life back together, to try and deal with the past”.

Byrne said: “If you’re the child of an alcoholic you don’t have a sense of what normal is so you invent models to live up to, so you become this incredible perfectionist and then you flay yourself remorselessly for not living up to those standards.

“And it’s a really common trait and it makes for a life of failure because no one could ever possibly live up to these impossible benchmarks that children of alcoholics invent for themselves.”

 And he said he was speaking out about it now because he didn’t want his three children growing up in a world where seeking help is still stigmatised.

“When you’re the eldest son and you’re a little boy, you’re just trying to make everything right, you’re just trying to make everything perfect and you’re just so focused that, that you just don’t dare tell anyone,” he said.

“You build this six inch armour plating so nothing can penetrate it and hurt you and the reason I actually had to go into counselling was that taking armour plating off for the first time, making yourself vulnerable, it’s so weird that you just fall over.

“It’s taken a long time to just put together a picture of the past.

“The way that I dealt with things and moved on was by burying all my childhood memories – I would look back on childhood and it would be a desert.”

He said counselling filtered back memories “like water through a bed of sand”, and that it was like putting back together a smashed stained-glass window by picking up the shards of his life: “And they’re really sharp and they make you bleed, and it’s really really painful.”

But he added: “Unless you build that picture of the past you’re not a whole person and it’s impossible to move on.”

He wants a huge investment in mental health services so they are available in schools, communities and medical settings.

And he wants to rebuild the safety net that helps people deal with trauma to stop them slipping through the cracks into homelessness and self-medication with heroin and alcohol.

“As a country we find some of these things difficult to talk about but unless we normalise this conversation then we are not going to make it normal to access help when you need it,” he said.

“I don’t want my kids to grow up in that kind of world, I want my kids to grow up in a world where it’s okay to reach out to help if you’re hurt.”

Byrne said he believed a life in politics made it harder to be frank about his problems.

But he joked that a career which has seen him demonised by the Tories for leaving his Treasury successor a note saying “there is no money left” after the 2010 election meant he now had little need to protect himself any more.

“I think it was harder to start with because politicians are still a little bit obsessed with image and I think for a long time politicians have been really fearful about looking weak.

“I’m blessed in that I’ve made so many mistakes in my life I don’t need to care about that any longer,” he jokes.

“I think politicians can shy away from confronting some of those things.

“There are a lot of children of trauma in the House of Commons, it’s partly because of that perfectionism in a way.”

He added: “I really struggled about whether to speak out about my dad, I felt for a long time that it would be dishonouring my dad to talk about something that I’ve been accustomed to bottling up with just tremendous stigma and shame.

“But my dad was the son of two alcoholics and there was no help for him so the decision I took was to try and honour the boy that became the man that became my dad.”