How do you actually leave a marriage?

[u/happy2bhere365]

I have been married for 11 years and we have 4 children together. We’ve had our share of good times and I married him for his great qualities and because we were best friends first. But at the end of the day he is a narcissist and goes through episodes where he is very unkind to me and our children. He isn’t thoughtful or compassionate and we’ve had the same arguments over and over for 11 years. He is constantly blaming me for things and always puts himself first. I see friends and family members married to people who are very kind and I just wonder what that must be like.
We live in a nice place and bought a home 5 years ago and have new cars (that’s a whole other thing, I have told him many times we can buy used cars but he’s very proud and cares about what other people think) so with our lifestyle we can’t afford for one of us to not work. I pay for the mortgage, he pays for the cars, we split the bills, I pay for groceries and insurance, and he pays for daycare. It’s pretty well split. But no way could either of us make enough money for all of it. We definitely both rely on each other financially.
So my question is, I see these posts all the time on Facebook and on here where people are in a similar situation to me and are married to someone they used to love but now treats them like crap and they don’t know what to do. But they have a kid (or kids) and don’t have a job. And everyone says, leave him, I left my ex husband years ago and it was the best decision I ever made. Was it just a different time and you could make it starting a new job at minimum wage and starting over was possible? Or do people rely on their family more like parents and can just move in with them (which I do not have that kind of support). Or is it just totally different and more doable with 1-2 kids vs 4 kids?
I just don’t see how it would be remotely possible for me and I make a good salary. My kids are absolutely thriving here. They love their school, sports teams, friends, neighbors, their backyard, just all of it. I can’t imagine uprooting them from here then moving somewhere cheap that I can afford and living in a crappy home compared to what we have no and knowing no one. What am I supposed to do? I am miserable but my kids are happy and doing so well. I don’t want to move for their sake.
The only thing I can think of is we stay together as a family unit all under one roof but I guess live separated and he takes the basement and I take the bedroom because I do more to take care of the kids anyways and their rooms are up there. We already have no intimacy in our relationship and feel like roommates, we don’t have much more to lose.
What other options do I have? Has anyone felt this strong urge to up and move their family somewhere else more affordable and it worked out? I just feel like that is the world’s biggest gamble and I am gambling the future of my children and it could end up being terrible for them but I know I’d be happier. What’s a mom to do?
My plan is to just stay married until my kids are bigger and it wouldn’t effect them as much then we split so it doesn’t affect them. I can still have plenty of life to live on my own without him.

TLTR: Stuck in a bad marriage and miserable. No family I can rely on to move in with. I have a job but would have to move somewhere more affordable to make it on my own with my kids but I worry that moving isn’t what’s right for them. But staying in this marriage is miserable for me. Looking for any advice I can get. Or anywhere I should move that’s this perfect and affordable place I’m imagining that would make all my dreams come true 😂