What did you learn about relationships when you were growing up?. Did you see similar at home too?. Controlling behaviour is abusive behaviour and is all about power and control.
The fact that you even have to ask such a question re stay or go is worrying and shows me that your boundaries to date re him have been far too low to the point they are almost non existent. You know this is wrong though otherwise you would not have posted so there is hope for you and your kids. But you and he need to be apart now, you and he should not be together any longer. The longer you stay with him as well, the harder it could become for you to make the break.
You will ultimately have to ask yourself how and why you got to this low point in the first place and address those issues re your own self.
He is not a good father to his children if he treats you and in turn them with the utmost contempt. Women in poor relationships as well like this often write the "good dad" comment or versions of it when they themselves can think of nothing else positive to write about their man.
What do you want to teach your children about relationships and what are they learning here?. Do not continue to teach your children that a loveless relationship with controlling behaviour, cheating behaviour and or weed in it becomes their norm too.
Staying for the children in such circumstances is a particularly bad idea and never a good one in any event. The children are not glue and should not be used as the glue to bind you and he together. They are NOT going to say "thanks mum" to you for staying with him for really your own reasons (because its) somehow "easier" or "more familiar" to you. Staying because of them frankly is stupid and they will tell you as much as well and tell you too that you put him before them.
I am also wondering if you are confusing love here with codependency; you may well be codependent in relationships. His primary relationship is with weed, not you and not your kids either. You've certainly propped him up and or otherwise enabled him to date and its been to yours and your kids detriment. He will need far more than a mere short course of addiction counselling; he could well go back to weed as soon as the counselling finishes. If he has also done this at your behest then it is highly likely it will fail.
Do contact Womens Aid as well, they can assist you here also. Abuse like this can take a long time, years even, to recover from, and you people have more than suffered enough at his hands already.