No flaming from me, either, justsofs.
You've started to be brutally honest with yourself... but you don't be brutal on yourself. Just be honest.
What do you want to be?
WHO do you want to be?
What do you feel when you picture yourself in 5/ 10/ 20 years time, either still in this relationship... or away from it?
I so wish you could meet and talk to my Mum. I hope you don't mind me telling you her story.
She married my Dad when she was just 20, and my bro came along 4 months after that, then me 3 years later. She was an intelligent, beautiful woman but painfully shy and had difficulties forming friendships. She had lots of acquaintances and was always outwardly the life and soul of the party but had no one she could properly confide in. She was an only child and crippled with a lack of self esteem and self confidence.
My Dad was 5 years older, handsome and hard working but bitter, cynical and old fashioned from a young age due to a pretty sh1tty upbringing. In fact, they both had sh1tty upbringings and that's what brought them together.
Dad wanted a traditional, stay at home wife. He belittled everything she tried to do (she was very creative) although she did end up with a better job and income than him (which just made him more bitter). He was never physically violent to her but was always bad tempered, distant and untrusting.
It took her over 30 years to walk away from this unhealthy, controlling relationship that made her so unhappy. She only stayed for me and my Brother, because she was scared of being alone and scared it would mess us up and that makes me so sad... for both her and my Dad, as it goes. She was a fantastic Mum, but from a very young age I knew she was unhappy. It took her a long time and a short affair to find the courage to leave.
My Mum is really, really happy now with my lovely Step Dad, but it took a bit of learning, growing and adjustment to get to that even after she left Dad. She actually went a bit wild - in her mid-50s! - for a while, experiencing the things she should have experienced as a young woman. She had crazy, fun relationships - some of her stories make me go 
all at the same time and her... ahem... toy drawer is a sight to behold.
She also experienced proper heartbreak, learned that she could paint, learned that she can't really sing or act but loves it anyway... then met my Step Dad who has finally enabled her to become the woman she was meant to be. She's amazing, my Mum... She's 63 now, and looks ten years younger. But she wasted so many years in an unhappy place.
I don't blame her for staying with Dad and fully understand and respect her for why she did, but I think she should have left years and years ago. We would have been ok, and maybe Dad could have experienced new and different things too and perhaps learned to be less of a twat... although I suspect he would have been a curmudgeonly old git come what may.
Sorry for going on a bit.
Keep talking on here, talk to friends IRL if you can, don't be hard on yourself but be strong. If you decide that there is something in your relationship worth working on/ staying for, then maybe counselling would help as someone else suggested.
But don't stay for the sake of the kids.
Take care of yourself
xx