I have to differ with Dr. Paige, because I've written book chapters on divorce and children of divorce, as well as a doctoral dissertation on the love lives of children of divorce, based on research and interviews with hundreds of my students in Psychology of Relationships. I'm not going to argue that you should not divorce "for your children's sake," but I'm not going to sugar-coat the effects of divorce either.
Children of divorce unconsciously do not trust marriage, and expect it to lead to divorce sooner or later. Since they're helpless to prevent their parents from divorcing, they'll do what they can to be unusually self-reliant (a good thing) so they don't need to depend on a partner for their basic security. They'll be hypervigilant about how to keep their security in an unstable parental landscape, if the divorce takes a long time before reaching a stable outcome. They'll be hypersensitive to anything going wrong in a love relationship of their own, play their cards close to their chest, be both passionately hopeful and self-protectively deceptive and keep escape avenues open, to make sure they don't feel helpless in their own love relationships.
A lot depends on how amicable the divorce is, and especially how cooperative the ex spouses are in child rearing afterwards--but one spouse can't force the other to be cooperative, when 1/4 are good-friends-cooperative and 1/4 are enemy combatants. Divorce children are clever at getting what they want from each parent separately, and play them against each other. They are unlikely to trust that a "we-ness" of lovers who marry each other "till death do us part" can really exist, because interview research has found that even after 15-20 years of marriage divorce children are still worried that something will strike them down. Is that awful? Well, there are worse things, like being exposed to parents physical abuse of them or of each other. In that case the children may also doubt their own ability to parent safely--but the research on that is scant, compared to that on the persistence of divorce-proneness & fear of helplessness in love relationships, which leads people to be too devoted to "holding on to their own power," like many people who are themselves divorced, including psychotherapists, who aren't immune to any of these effects, because they are unconscious. Loving requires a balance of surrender and self-reliant power, and a person may be able to achieve that balance if he or she is aware of his/her unconscious needs for power and control in love relationships.
What did your kids experience during your 2 yr separation? Were they shuttled between yourself and your husband? How would a post-divorce arrangement be different than that? Don't virtually ALL kids grow up with some deficits and psychological wounds? Yes. Children with an alcoholic, drug-addicted or mentally ill parent are all scarred as demonstrably as children of divorce. Is it possible that the kids could have a better relationship with each parent if you were each happier because you weren't living together? Yes, and I've seen a few students that had two loving dads and two loving moms who cooperated well in supporting them, and these young adults really did express the "it'll all work out fine" attitude that Dr. Paige expresses.
Some parents wait until the kids leave home to divorce, but that's not as easy in the hard economic times of today. Could your husband find someone else to make him happy? It's not your problem, but it sure would be nice if he could. Perhaps if you let your husband stay on the condition that he tolerate your intimacy with the other man, he'd be inclined to find the same thing for himself. That's a long shot, and I sure wouldn't count on an "open marriage" agreement to proceed smoothly, though it might.