I think a bottom is more a state of mind than an event - it's the point where you realise you can't live like this anymore - and I certainly hit that point on pot.
But many of the folks I know from back then still smoke all day everyday...presumably they're content to still live that way.
I can't say whether your husband will end up being like me or like my smoking buddies.
I think the main question here should be - what exactly are you prepared to put up with for you and your kids?
You'll find a lot of support here - we have really good family and friends forums here too - I hope you'll check them out as well
Welcome!
D