oh i believe he loved her indeed, if else why did he keep a portrait of her, and keep mentioning of his first wife to his son? yep, he love her, but he love power more. anyone can be blinded by power, and Chow's character is the kind of person who would do anything for a taste of this, and what's scarier is that he doesnt regret those that he had wronged. hence, he's willing to go as far as to attempt to kill his first wife again, for fear that his secrets would leak to the public.
i cannot fathom why he loves his first son more than his second, the second being more capable, brilliant and a thousand times more reliable in battle than the first (okay so he lost the final battle, but Chow had an informer, the weakling, coward first son of his
we know if Prince Wan were to lead any army at all, he wouldnt last a second). the only explanation is that this son is the only thing that he can remember his first wife by.
plus, although chow decided to replace Prince Wan as crown prince with his second son, Prince Jai, he wouldnt have decided this if Prince Wan had not said yes to it. Prince Wan was relieved when Chow decided to replace him, cuz he's unlike his father who crave for power. All he wanted was to escape his father, and have a peaceful life with his love (lol poor Chan....
)
just my 2 cents