Leaving my ex (and more importantly, uprooting my kids from their home, school and friends) was the hardest decision I've ever made. He dragged me through court 3 times, and I'm still repaying legal debts. I was broke, living in a hovel and utterly miserable at rock bottom.
But he was an abusive c*. 7 years after I moved out I have retrained, got a full time job and found my true vocation. The kids are happier than they could ever have been with a mother who was subject to emotional and financial abuse. We have had adventures beyond his wildest dreams (youth hostelling, French holiday on a shoestring), learned so much - resilience being the most important realisation - but also budgeting, dealing with our own crap, prioritising, only sweating the major stuff etc etc.
I only have to worry about myself and the kids now. Not him, not walking on eggshells all the time, not dreading his key in the door, not worrying about what ludicrous tale he'd invent next (apparently I was cheating/spending all my time out of the house/downloading child porn etc, driving myself mad with worry over stuff that I KNEW wasn't true but he was great at gaslighting).
He rarely sees the kids now, we don't communicate due to his abuse on the phone/texts.
So. Yes it's hard. But if I was still married I know it would be so much harder, and every day I'm reminded of how far I've come.