My hat's off to you, that was an excellent summery of the most turbulent of times when men like Fisher and More were killed for opposing Henry VIII and his enormous appetite for anything he personally wanted.
Henry VIII has always been a fascinating figure to me. On the one hand, he was a tremendous visionary and leader. After all, look at what he managed to get accomplished. On the other hand, I think he was very insecure. It bugged him that his father, the first English king in several centuries to not have the name Plantaganet, was always somewhat received as a usurper. I think this goes a long way to explain why Henry VIII consistently moved swiftly and ruthlessly to stamp out any hint of rebellion.
Henry's confrontation with Rome was many, many years in the making. The origins go at least as far back as the Magna Carta. The annulment question was simply the straw that broke the camel's back- much in the same way the murder of Franz Ferdinand was the spark that ignited WWI.
Henry was always a devoted Catholic (in mind if not always in body), but in his mind, England came first. In order to assure a smooth succession without another civil war, he needed male heir, and a queen who could provide one. Catherine of Aragon had grown too old, so things, however ugly (though routine throughout the middle ages), needed to be done for the sake of the realm.