Based on what little is revealed of is past in the game Jack was just a weedy office nerd with a massive complex of some sort who somehow blackmailed and murdered his way to the top of the company.
The game also seemed to be implying that he used and later murdered his wife (or that she died as a result of Jack's actions) I forget the exact words but someone was attempting to talk Jack into stopping the experiments on Angel and Jack strangled him for mentioning his wife.
The guy was nothing but a cowardly scum bag and as for people thinking that he cared about Angel no he really didn't and if push came to shove he would have cast her away like anyone else he no longer had any use for.
He also had a tendency to throw child like tantrums when he didn't get his way.
One of the key things about Jack is that while he isn't so great, the protagonists and the people they're protecting either actively or indirectly are absolute scum. You have murderers, rapists, slave traders, arms dealers, mad scientists, inbreds, psychopaths, cannibals, pyromaniacs, extremist cults, monsters of ungodly levels of horror, and Scooter.
The place deserves to be burned, and paved over. That much is certain.
You sound like you agree with Jack. --- Will you take the Rocket Launcher? >Yes No