I know...it's so hard to distinguish.
I usually follow this rule of thumb...If a request from someone makes me uncomfortable then I won't do it for them. You felt uncomfortable for a reason....this responsibility belongs to your husband. That comment he made was to inject guilt into your decision thereby causing you to rethink your decision...end result...maybe he'll get what he wants. Maybe you can suggest that he make arrangements with his exwife. They are their children after all. So you can stay home and take care of your kids. Just my opinion.