I feel you OP. I've been on the same countdown to the children being grown so I could leave and start living the life I want, not the one I'm shoehorned into by a controlling 'D'P. It's soul destroying, and saps everything out of you.
I'm now 5 months post separation, and things are better than I could have imagined. I was lucky to get a job in the last place I worked before leaving to have DS, so I'm financially independent. The DC are now sleeping better, the cat as stopped stress weeing on the doorstep multiple times a day, the house has never been more organised, and I spend much more time doing nice things with the DC than I did before. We do much more in the house, such as baking and crafting, because I'm no longer so desperate to be out of it and away from their Dad, so I'm spending less on entertaining them. DS has positively blossomed in the absence of his Dad.
We're still ironing out the kinks in the contact situation (complicated for various reasons), I actually have more disposable income than I did before the split (I had no hand in out finances for years, as I didn't earn, so I have no clue where our money went, we should never have been struggling as badly as we were), so I've been building up some savings as well as clearing all of the debt I discovered during the process of changing bills and accounts into my name.
Everything hasn't been a complete bed of roses, my energy levels are still lower than is typical for me, but it's a physical tiredness as opposed to the soul deep emotional drain that it was a few months ago. DD has found the change hard, she's a Daddy's girl, but she's adjusting, and is still happier overall.
I strongly urge you to do some research into the reality of how comfortable financially you would be if you broke off the relationship. I was worried about even covering the bills, but in reality, so long as I consider everything I spend, we have enough, plus a little extra left at the end of the month, and I'm not on a particularly high salary (teacher on a 4 day a week contract).
I deeply regret not being firmer about him moving back in when we separated during the first lockdown.