Lebron carries this pitiful organization for 7 years, they can't make anything happen, and they freak out when Lebron moves on to play with some people who actually want to win? The only real betrayal here is that they wasted so much of his career.
LeBron brought them their first NBA Finals appearance. What did they get him? They brought in a bunch of guys off the streets like Wally Szczerbiak, no PG, etc.
But he had to do this. If he towed a corporate line and made some random generic response like "We regret LBJ did not stay and wish him well. We appreciate the years we was here, and regret we could not continue our partnership. We will continue to strive for our goals to win championships", Cleveland folks would have just laughed, gave up, and moved on.