My non-father committed suicide when I was 13. All the weight of my N mother was thrust upon us after he was gone. As a child growing up, naturally I would have preferred my parents to stay together because we were a family and that is what I knew. Having him there everyday meant everything to me and gave me the tools to build a healthy self-image. As an adult now I wish for my father's sake that he would have had the strength to leave her and find someone who would have treated him better. That would have crushed me not having him there all the time though. As a child I needed him around all the time to feel loved because I felt no love from my n mother.
I don't want to tell you what to do because every situation is different. Your kids in their situation may have different needs than I had.