Gabster:
Hugs for you - Writing this down is a good first step. I hope it can help you see what has happened. Maybe making a couple of lists of stuff that has gone wrong from both sides so you can talk about it and try and go forward.
I hope you can make him understand that it is worth saving for the sake of the girls. It is really unfair of him to just land this on you without having a period of you being aware of what was happening so you can change things from your end and he from his. You will have to make him see why he married you and that you are still the same person.
I hope you can sit down together and talk it through a bit more - is there someone else that can make him see not listening to you / giving it another chance is totally unreasonable?
Just some ideas - 
Thanks Gabster. I can completely see what has happened and what has gone wrong but he simply won't give me the chance to try and put things right. I've tried talking to him about giving it a go for the sake of the girls, but he says that they are just over two, they won't remember any of this. I told him that I was still the same person, but he doesn't want me.
I know my parents will want to talk to him and try to make him see sense.
Thanks so much for your advice and ideas xx