3 weeks before their engagement party, her fiancé called to say he'd cheated.

In July last year, in my second week of work in a new job and three weeks before my engagement party, my partner of two years called me at 8am on a Monday morning crying.

At first he was crying too hard to get the words out. I asked him repeatedly what was wrong. Was he hurt? Was he in an accident? Had something happened at work? No.

He didn’t need to say anything else. I knew. Two weeks prior, at a small party I hadn’t attended, he had gotten black-out drunk and slept with someone. We had been engaged three months.

The next few days were the worst of my life. Obviously there was anger, and hurt and disbelief. My partner tried to assure me that yes, he was very happy and no, he absolutely did not want to lose me. But he still couldn’t tell me what had happened or why he ended up in this situation.

Over the next few weeks we struggled. I would wake up at 2am to find him sitting on the floor in the doorway of our bedroom, watching me sleep. We discussed our future, whether there was one or whether we should break up. My partner cried, frequently. More frequently than me. More than was normal, even for someone in his situation. Then he stopped getting out of bed in the mornings. He refused to go to work. A feeling of unease started to uncurl in my stomach. I started thinking back across the course of our relationship to other times when he’d refused to get out of bed, or drunk too much, or cried too easily.

I had known he sometimes ‘felt down’. I knew that sometimes he wasn’t feeling motivated to go to the gym or to do the dishes or go to work. I knew that before we’d met, he had a reasonably significant drug problem. I also knew that there was a history of mental illness in his family, of anxiety and depression.

But he’d seemed fine – things were going great between us and we had so much to celebrate and look forward to. Surely he had just drunk too much and made a really poor decision aided by someone equally as inebriated and with severe emotional baggage of her own. But he wasn’t dealing with what he’d done at all – in fact he seemed to be coping worse than I was. Almost every day he would wake up crying, and I would have to physically pull him from the bed. I would dress him and get his things together to send him to work, terrified he would lose his job.

Eventually, I persuaded him to go to the doctor. The doctor wrote him a referral to see a psychologist, and the sessions seemed to help. At the end of session five, she signed him off. His indiscretion and subsequent depression seemed situational, she said. Somehow, we moved on. We stayed together and I tried to be supportive while trying to work through my own anger and hurt.

Then about five months later, I started noticing that he’d stopped going to the gym again. He wouldn’t help around the house and was dragging his feet getting to work. One Tuesday evening, he went out for afternoon beers with a mutual friend. He came home drunk, when he wasn’t supposed to be drinking, and the look in his eyes showed me that things weren’t going right in his head. We had a fight. He started spewing out hateful, hurtful, untrue things. I treated him like he was stupid; he was worthless and he had nothing to give to anyone. He had nothing to offer a future family. I started to cry and he disappeared into our bathroom. I heard several loud thumps and some screaming as he punched a massive hole in the wall.

In the morning, I took him straight back to the doctor. This time, I made him sit down and explain everything. He was prescribed medication, counselling and a strict diet and exercise plan.

He started taking the medication immediately, and after about 10 days I could see the positive effects. But despite the improvement evident to me, he was still reluctant to take the medication. We are now two months down the road and he still feels he doesn’t need medication and doesn’t want anyone to know he is taking ‘crazy pills’. I hope that over time, he will feel more comfortable and be able to admit that medication helps him.

There is still a lot of stigma around depression and mental illness. Some of our family and friends know what we’ve been going through – lots don’t. He hates to tell people, fearing they will see him differently or offer ‘awkward half-assed pity’. I hope as time goes mental illness won’t be as misunderstood and he will feel more comfortable talking about it.

It has been a hard battle for both of us, and it’s only just the beginning. His doctor says he has probably always been battling depression, but self-medicated with drugs and alcohol. Above all, perhaps the hardest thing is seeing the way his self-worth deserts him when he’s feeling down. He cannot see through the fog to remember that he is caring, he is smart and he absolutely has something to give. This sense of worthlessness is perhaps the scariest part of all, and what leads so many people to take actions that can’t be undone. If there was only one thing I would want him – and anyone who is struggling – to always remember, it would be this: you are loved. You have worth. And the world is absolutely better with you in it.

Would you forgive a cheating partner because of their mental state? How would you cope with a partner who has depression?