Let me start by saying I don't believe people should stay in bad marriages. I divorced when my daughter was about 8, and it was mostly for her protection, because her dad had become extremely emotionally abusive, and was never much of a provider, anyway. She was terrified to be home alone with him, felt safer away from him, but even so, she suffered mightily over the dissolution of our family. It took a couple of years for her to feel reassured that we were better off without him. And many more years to work out the complicated feelings that a divorce, and my later remarriage, burdened her with.
And most kids hate being shuttled back and forth for visitations. Divorce can be really, really hard for kids – it's more the rule than the exception.
So you might be a better and more patient mom, but that may still not make your children's experience better overall.
Just a thought – you say he is a good man. You had strong reasons for marrying him. Those qualities, needs and dreams may still be present, just dormant and waiting for the right kind of nurturing. I strongly recommend that you explore that possibility before giving up, because divorce is hard, expensive, stressful on ourselves as well as our children. We promise "for better or worse," and lots of marriages endure years of worse before the better can emerge again.
Consider counseling for the two of you, and if he won't go, at least get it for yourself. Even if you don't end up holding the marriage together, you'll get support in making your exit as sane and peaceful as possible, and reducing your child's inevitable distress.