Sourdough,
re your comments:-
"I don't want to leave him full stop, because we do have alot of great history, two fab kids and actually can have a brilliant time together".
Really?. You don't say. Am sorry for the cynicism but are you really being honest here with your own self?. You're kidding yourself if you're really thinking like this; this is denial on your part. Denial is also a powerful force.
"His dad was a selfish prick and I fear it runs in the genes. He's not like it all the time, but he is too much of the time".
We learn about relationships first and foremost from our parents, what did his teach him?. Its not genetic y'know.
Also what did you learn about relationships from your own parents?. Did your Mum act in such a manner towards your Dad?.
"I am a strong woman and have always stood up to him, but have made a rod for my own back by taking on responsibility for everything. He needs a wake up call because this can't go on"
No it can't and someone is going to have to break the impasse here and on a permanent basis as well. You going away with the children for a few days won;t change his attitude; he'll just enjoy your absense even more. You haven't been able to fully stand up to him and look where you are now. He has controlled you further by isolating you from family and friends.
You've turned a blind eye to it all - you have had suspicions which could well be correct that he has had an affair. Your liberal "french" attitude (actually its not really a french attitude at all but some french women do turn a blind eye to their men having affairs much to their own detriment) is costing your dearly.
You have certainly made a rod for your own back by allowing yourself to be treated like this, is this really what you want your children to see?. What are you teaching them about relationships here?. Where's your actual self respect and esteem?.