The most significant mistake my mother made in her marriage.

My parents’ divorce was unexpected to all those who existed in the orbit outside their marriage.

To the outside world, theirs was a relationship full of commitment and respect. Mum and Dad enjoyed a marriage signposted with cutesy traditions; weekly trips to the local market, cooking dinner together, and nightly chats around the dining table were fixtures in our family life.

They enjoyed 30 joy-filled years before they parted ways. Well, “joy-filled” to the people on the periphery, at least.

For the two people inside that marriage, there was one issue that was carving out a hole. Day by day, week by week, the rotting of their union spread from the middle. Like poison, it branched out from the core to the extremities until the whole thing became a cesspit of tension and discontentment.

Only then did my siblings and I learn that my parents’ marriage was a hollow facade – a shell of children and nostalgia and not much else.

By the time Mum and Dad announced their “surprise split”, my sisters and I were adults, on the cusp of leaving home for the thrills of travel and career. We sat around the living room, shell-shocked that our father was beating us to the chase.

I’ll never forget what my mother said mere minutes after my dad walked out: “Do any of you know where the passwords to our bank accounts are? I don’t know how to get into them.”

At the time I thought that, perhaps, Mum had a bad memory. Too many bank accounts, too little time to remember all the lengthy usernames and passcodes, right?

Wrong.

My mother had gone decades without knowing how much money they had. Despite being the main breadwinner, and working full-time, she had gone years without access to her own paychecks. She had handed over financial control to my father, completely and naively, year upon year, until he turned to her one day and said, "I'm done with this marriage".

Why? Because she simply took no interest in what her money was going towards - she believed my father understood matters of finance better than she ever could.

"What was I supposed to do?" she asked us when we looked at her incredulously. "Your father was always better with money than me."

It was as if 'money' was a foreign language akin to Mandarin; something my mother was inherently incapable of translating. She had, slowly, morphed into a constant state of hopelessness and helplessness. Money is hard. It's all too daunting and confusing. So why not let Mark control it all? He seems to understand.

As my mother's grip relaxed, my father's only strengthened. He had no qualms with all the power being at his immediate disposal. Some days, he'd arrive home from work to inform us that he'd spent $10,000 on something foolish.

"Well, we must be able to afford it," my mother would tell herself.

And so, one April day in 2012, my mother's life unravelled, and she not only found out that she was about to become a 50-something divorcee, but a woman with far less money to her name than she had ever expected.

Now, five years and a new house mortgage on, my university-educated, smart mother looks back at the dynamic in that marriage as the biggest mistake of her life. "I was a complete and utter idiot," she tells us at family dinners. "I let myself be a coward and stay in the dark."

Listen: How divorce can change a life for the better. (Post continues...)

Slipping into that pattern of control and passivity didn't just happen the day my parents said "I do" - it was laid, brick by brick, so slowly that when my mum took a step back, she realised there was a giant wall between her and the money she was earning.

She's not alone.

A report by the ABC this March revealed that approximately 16 per cent of Australian women have suffered financial abuse at the hands of a romantic partner.

No matter what way you twist it, the problem of financial abuse is insidious and widespread. Many women around the country have days like my mother did in April 2012.

Days where they sit there, faced with the reality that, no, we couldn't afford it, and yes, now I have been plunged into the scariest of deep waters, with only a rickety and decaying boat to support me.

If you suspect you are the victim of financial abuse, Mamamia urges you to seek support here.