Definitely the year after DS2 was born. He is autistic (not diagnosed until he was at secondary school) and had severe ARFID to the point of starvation. this was before the internet, before MN and I didn't even know the term ARFID until he was about 10 years old. there was zero medical support. He threw up everything he ate and screamed all night long. He also had a number of complicated physical issues and a minor physical disability. Again almost zero help from medics.
I didn't have more than 45 mins unbroken sleep for the entire year. I hallucinated from sleep deprivation, had severe PND, forgot my own name, couldn't eat. I accidentally gave DS1 some strong adult medication as it looked like his medication when he was running a fever of 42C. DH was useless - we nearly split up. He would go out boozing at lunchtime (in the days when this was a thing) and spend more on wine in one lunchhour than he gave me to look after both children for a week. He earned a lot but we didn;t have a joint account and I was broke.
DS2 was so ill and so difficult - screaming and projectile vomiting all day long, refusing even tiny mouthfuls of milk unless I held him in a particular way. feeding him just 30ml of milk took up t two hours. Meanwhile DS1 was ignored, ignored ignored. No one could look after DS2 except me, so I lost an absolutely brilliant job that would have been the making of my career. I tried to do it and failed badly due to sleep deprivation then had to step down. The person who offered me the job who had been a mentor of mine never spoke to me again. I had no job and when my maternity leave ran out, I relied on child benefit. It felt like a living hell that would never ever end.
Eventually DS2 turned a small corner, DH and I had some very serious heart to hearts and I forced him to become more involved and give me better access to mony (we didn't have a shared account.) I set up my own business working from home -very very small scale at first but by the time DC were school age, it was taking off.
Twenty five years later, that business earns good money and I enjoy it. Still tiny and run from home, but work that I love at better rates of pay than if I was employed to do it by someone else. My screaming, starving baby is an adult with a first class degree from a good uni, a good job, his own flat, a girlfriend, a brilliant semi-pro hobby he loves, lots of friends and is a bit of a foodie, ironically. Way more adventurous than I am. DS1 lives abroad, doing a well-paid job he loves, has a gorgeous partner, loads of interests, visits us often.
DH and I are happy together. If MN and the internet had existed at the time, it would have urged me to LTB and I nearly did. But I had no money and knew trying to earn a living on top of the horrendously exhausting job of keeping DS2 alive was an impossibility. I am glad we struggled through.