>>>He is all sweetness and light to me until he is anything but. And it seems to be simmering just below the surface.<<<
This resonates. My now-X BH is a charming, wonderful person. Unless he is angry. And the anger is always there, just below the charming, sweet surface he so carefully maintains. BTW: my XH has a drinking problem as well (though I don't think it's limited to just drink - more like addictive to various substances)
Like you, after D, I did anything within my power to spare my two kids the harm of a hostile break-up, and for some years we continued doing things in harmony, even celebrating b-days, X-mas as a family to make the transition as painless as possible to the kids.
What I failed to admit to myself (until it was too late) is that the reason that I spent so much time with him was because the anger, though primarily directed at me, was affecting the kids, too. They sensed it. It scared them.
It was the main reason I stayed close - to protect them.
Still, if anyone would have asked, I felt absolutely sure he would never harm the kids. I told myself this and really believed that.
But my own actions were belying my beliefs. I felt increasingly anxious about leaving them alone with him during visitation, and I increasingly bent over backward to make him pleased with me, to soothe his anger so he could not take it out on them.
Like you, I reached a point where I would do anything short of remarrying to keep the peace. And at some point I even considered that. To provide the kids with a warm, two-parent home. But deep down: to save the kids from harm.
Why am I telling you this? Because a year ago, I finally found out that I was a fool for telling myself his rage did not damage the kids. A fool for thinking it would be better for the kids if we stayed close and if I kept the family together as much as possible... A fool to think I was the real and only target of the rage, a fool for believing I could diffuse his anger, for believing he would stop well short of hurting our children. A fool for not taking my kids far, far away and amicable co-parenting be damnded.
A year ago, I discovered he hurt my children, had been hurting them and terrorizing them for years. They were to scared to tell me - and as driven to keep the peace and keep the family together and save us all from any unpleasantness, as I was. He had been secretly hurting the oldest for years. Only when he turned from physical abuse to sexual advances, did she finally find her voice and speak up.
People who behave like your H and mine are sick. They do not limit the damage to us only. We are not that great and powerful - they are equal opportunity 'destructors'. And you *cannot* keep your kids from harm as long as he has any impact on their lives. These people *will* harm your children. They will harm everything and everyone that they perceive has wronged them (including, in your case, the innocent betrayed spouse of your OM).
You may think I am over reacting. But my exH is still a much-loved, highly respected member of the community. Very charming, Sweetness and light. Meanwhile, I deal with a teenage daughter who cannot sleep for the nightmares of Daddy touching her, pushing her down the stairs, and laughing at her, and mommy groveling, rather than protecting her.
Please be aware. Be alert. And get your kids out - at the first sign of trouble.