LH is asking very pertinent questions which are actually at the crux of your pain.

I think you not only need to ask these questions, but you need to explore them with a counsellor.

For me, my fears were:
a) what would happen to my children, how their short and long term futures would be effected
b) would I be okay on my own
c) fear of the unknown

These are the fears that keep you trapped. Your current trap is that your brain knows logically that the best way forward is to walk away happily from her - but your emotions and uncertainty and fears like a) b) c) above can control your brain and you end up making emotive, not intelligent decisions.

The reason that some days you are fine and other days you crumble - is because of the power struggle between intellectual reasoning and emotional parts of your brain. They are fighting it out, and so you wobble between two extremes.

Getting to the bottom of your fears allows your intellectual brain to slowly retain control in preference to your emotions.

I’m my situation, all three were things I shouldn’t have worried about.
a) Kids are MUCH more resilient than we think, and much more resilient than adults. Adults like routine and structure and repetition, and struggle without it. A child psychologist told me “you underestimate your kids ability to understand what has happened, and their ability to adapt, and their unconditional love.” Looking back, she was 100% right. My kids haven’t been stunted by divorce - they’ve thrived.
b) I was okay on my own before I got married, why the hell wouldn’t I be okay on my own after? Also, you’re not on your own with your kids, family, and friends, and work colleagues - in all those facets of life you will be the same with people around you. It’s only in the relationship part of your life that you will be on your own - and most likely not forever anyway.
c) Everything in life is unknown the first time. Unknown can be good. Uncomfortable can create growth. People who are comfortable and know everything, eventually become very boring and sad people. Would Nelson Mandela have become one of the world’s most incredible human beings had he not had to face adversity?

You are in what many will describe as the toughest time of your life Rockon. Trust me when I say it’s only temporary, and that one day, you may look back on your separation and reconciliation or acrimonious divorce as one of the best things that could have happened in your life.

I certainly do.

Please don’t reach out to her. You will absolutely regret it.