Wishicouldchange - I'm sorry you're going through this.
However, I am sure that he's not going anywhere. He is playing mind games with you, if you keep on telling him how sorry you are and it's all your fault he will use your hurt and low self esteem to make you feel even worse.
Stop saying you're sorry for things that you know are not your fault. Stop trying to make things better by agreeing that you're to blame - after all this is what you've been doing, and it's not worked has it?
Please realise what he's doing and that he's being abusive. You are not to blame for this, but you must do something before you're dragged down to a point where you cannot think straight.
You know it's not right, or you wouldn't be posting here, and things can change - or rather YOU can change.
And I absolutely do not mean that in the same way that you say you need to change, I mean that you can change the way you respond to his critisisms, do not believe what he says, realise why he is acting like this - he is a bully and you are not to blame - so don't believe him and become upset by it.
You cannot become a 'better' person so that he will be nice to you, it will not matter what you are he will still be this same way he will just find something else to critisise you for.
Now, I don't believe it but I may be wrong so, if he says he is leaving and has it all sorted, well, honestly would that be such a bad thing? I know you don't want your marriageto end, but is this marriage making you happy? Will you be any more miserable if he were not around everyday?
It will give you a chance to recover a little from the constant stress you are under at the moment and you may be able to see things a little more clearly.
However, if his plan is that you leave the house - get advice straight away, don't step one foot out that door!
Good luck and let us know how you're getting on x