Just to expand on my original post which is about my current situation.
My parents remained in an unhappy marriage until my sibling and I left home.
It was pretty awful.
Dad was an alcoholic, there was low level violence a few times.
Mum was quite volatile, but definitely the better parent.
As a teen, I desperately just wanted them to separate.
However, controversially, I'm now relieved that they stayed together. My Mum eventually divorced my Dad and ended up, very quickly, in another bad relationship. Another alcoholic.
She also had a short promiscuous period after they separated. Knowing what I know now, I'm glad that my Mum stayed with my Dad and didn't leave sooner. I think we would have gone through a lot of upheaval due to mum's volatile state and low self esteem. I've no doubt she would have had a string of bad relationships. I'm glad we didn't have to go through that and I've no doubt we would have been carted off to another part of the country if she had met someone far away. Atleast we had our grandparents close by and the stability of our friends around us.
I never thought I'd ever look back on things from this perspective and I know others would disagree.
My advice would be to get yourself sorted emotionally and mentally as much as possible on separation or even, beforehand if possible. It's not always a good thing to get up and leave as soon as things get tough. Preparation is key.
I've had a lot of therapy whilst still in my current failing relationship (which isn't particularly toxic) so that I can give my children and I as healthy a life as possible going forward. This has felt the right thing to do along with waiting until my youngest starts school for financial and emotional reasons.