Thank you all for your brilliant supportive replies. I wanted to update as have just lived through the worst weekend so far, I had a complete breakdown, became irrational and was not sleeping, not eating and allowing him to keep piling the hatred on me.
He returned again last night, with an attitude, I was still crying (have cried continuously which I didn't think was physically possible) I sat and listened to him going on and on about how he was feeling, how I didn't take any responsibility for anything, it went on and on. I sat there and as he talked I just had a moment of complete clarity, he was an idiot! He told me things about myself which were so far away from the actual person I am (and one thing I do do well is self reflection so know that I am not a hard faced cow, uncaring, avoid taking responsibility etc etc) as he spoke I just thought, you are talking absolute shite and rewriting our entire life into something it wasn't. You have rewritten the personality of the person you have spent your whole adult life with, to make yourself feel better but I realised that as much as he says all that, he knows that is not the person I am or was deep down, it is all to boost his own ego and to hurt me. He said yes I lied, yes I deceived you but I've said I'm sorry so what else do you want? It was like the carnage he was causing meant absolutely nothing at all, it was at that moment that I realised she was more than welcome to him, he is no longer my problem, does not define who I am as a woman and does not get to tell me anything anymore, not about how he is feeling, what he perceives me to have done (which amounts to me being occasionally a bit off with him when he was shouting at me and not sharing with him things I needed support with in my life, which I have said yes I did do that it was my own choice and I take responsibility for doing that, as when I did share things he would just get angry and turn it back round on me). He fails to remember the woman who was here every day, working, raising his children, providing a warm and welcoming home, loving and respecting him. never nagging, never complaining, supporting him through his challenges, welcoming him home every night, cooking, cleaning, running his errands, etc etc.
As he was talking I just stood up and said "you are only saying this stuff to hurt me, and you can't hurt me anymore than I am already, I know that it isn't true and if you believe any of the crap you spout to me, then you did not know me at all and that is really really sad. Do what you want, shag who you want, I don't care anymore"
I made myself something to eat, arranged a counselling session for today, went to bed and slept like a baby.
I don't want him, he is a moron, she is welcome to him and today is the first day of my new life! I feel liberated as well as heartbroken, betrayed and scared, this weekend was my lowest point and I know the coming months will be hard but know that I will get through them, I've even started to think about all the pretty pastel things me and my girls can fill our new home with! Thank you thank you thank you for your supportive messages, they really made a massive difference this weekend x