Once a cheat always a cheat? Is there any point in trying to save my marriage?

[BeenThereFeltThat]

If anyone wants the background I've posted about this before under this name.

Last night DH left his email account open when he went out and I saw a chat between him and the woman he had a 4 day fling with 3 years ago.
I confronted him about it when he got home and he came out with all the usual excuses:

'It was her who started the chat' No, actually it was him.
'Poor thing she's going through a hard time'. What about the hard time I've gone through since his fling(s)?
Bla bla fecking bla

He blames it on the fact I don't want to sleep with him, am a block of ice, have never been sweet or gentle or loving.

I blame all that on the fact that he has systemtically eroded my confidence and love for him due to his 20 years of cheating, since I met him in fact. He thinks I 'live in the past' that I 'love going over old hurts'.

You might at this point be wondering why I'm still with him, why I didnt leave years ago...well, he's fun (well he used to be...), intelligent, handsome etc etc and every time I found out about an infidelity he'd swear it wouldn't happen again and I, stupidly, believed him.

Problem is we now have 2 young DCs and last night he threatened me with legal action if I try to take them away from him, which I wouldn't because he's a good father but I had said 'what is the point, we shouldn't live together any more...them seeing us like this is not good for them'.

I told him I would love more than anything to be happy together, to have a great sex life with him but it's got to the stage where not just my mind is rejecting him but my body too. As if my mind and body are in collusion saying 'Why would you want to sleep with someone you don't trust? Why would you do that?'.

Also he won't take any responsibility for contraception, won't use condoms and I don't see why I should f*ck up my body with the pill or use other methods which are invasive.
I can't get pregnant again, am getting on and broke and there's no way I'm going through all that again just when the DC are finally starting to be easier.
It's easy for him to say 'let's have unproteced sex, nothing will happen' - his life would go on as normal and mine would be even more difficult.

I got out of bed and hid our passports as we already have flights booked to move back to my country later this year. He is coming with us but I think he may have a legal right to prevent me from going with them alone if things deteriorate. I said to him if you are coming with us then we have got to do something about our crap relationship. If you aren't prepared to do anything about it then don't come.

What a mess, how did things get this way?
Does anyone have any wisdom?

[SolidGoldBrass]

I often advise people whose partners are not monogamous to sit down and seriously consider whether they can accept the fact that their partner is going to have sex with other people, because if you choose to accept it (only do this if you feel you can live with it) actually all the stress goes away. You're not forever waiting and wondering about the next affair or hissing at every woman he speaks to, you're just getting on with life.

However, this man is not just a monogamy refuser, he's a nasty bit of goods: the no-condoms thing being the biggest indicator of this. Refusing to use condoms while being openly non-exclusive in sexual relationships is complete knobbery.
And when he says he 'wants it to work' what he means is he wants you to carry on coocking and cleaning and looking after the DC and appearing with him in public enough times to make everyone else think of him as Nice Respectable Married Family man, while he does what the hell he likes with no reference to you and no interest whatsoever in your wellbeing.
Get some legal advice and get rid of him.