When JF said that Élora left him what mattered/was important, he wasn't talking about their daughters. He was talking about the property and businesses in her name, and potentially a life insurance policy. He's exactly the kind of guy who would kill his wife, rather than see her get the house, custody of the kids, and any other assets and support in a divorce/separation, and I think that's exactly what he did.
As for the question that keeps popping up regarding why he keeps choosing low-IQ women, it's entirely about domination and control. They just don't have the mental capacity to push back in any meaningful way. And, frankly, I think he sees all women as retarded anyway, so it's just a matter of degree; whatever Élora got up to with sleeping around and public nudity and needing to be rescued off the street is, in his mind, a woman-thing, not a potato-thing.