I have a few points/questions.
Firstly re the money. You said it was in an overseas account (in the country you are moving to). How esactly did the money leave the account? Was it bank transferred? Withdrawn in cash? I am just trying to establish if you can identify whether the money went out in small amounts. I think you need clarity on where it actually went.
Next the drug deal. Was it here in the uk? In which case, surely your children are in more danger here? Or was it abroad? For me, I would want to be out of the country it took part in although I would be worried that if it came back to haunt him/you, you'll look culpable if you have "fled".
People are telling you to stay but I don't see it as that simple - your belongings have gone (haven't they? Did you find out if they have left yet?), you have no home - I think I read you rented and it has been re-rented on your vacation.
Did you say you have property in the country you are going to? You personally? Independently of your husband? In which case I say yes, go to that property but tell him you need to go alone for now, whilst he sorts himself out.
Do you speak the language out there? Have work identified? Have family and friends of your own (ie not his network?).
The children will be ok whatever you choose as long as you promote it in a positive fashion. It does seem to make sense to go because if you find it tough, presumably you can sell up and return here with some capital? If you stay though, you just need to make sure you are constantly positive and reassuring to them (I can say this with experience having moved several times).
Good Luck. Please feel free to pm me if you need an ear.