What are you teaching your children about relationships and basic human interaction by remaining in such a toxic environment? From a very early age, children emulate adult behaviour and model their own reactions based on their environment.
Try to imagine your children as grown adults, engaging in toxic relationships like your marriage...do that provide you with the adequate motivation to leave?
In the end, you'll leave when you are ready, but I'd gently suggest you consider the long term effects of *your* choices on your children's lives.
Perhaps, rather than the whole "intact family" ideal (which in my experience is often an illusion), what's keeping you there is fear of the unknown.