When King David heard all this, he was furious. Absalom never said a word to Amnon, either good or bad; he hated Amnon because he had disgraced his sister Tamar. 2 Samuel 13:21-22
After the kids are all grown up, David began to see just how dysfunctional his own family had become. David got furious at Amnon for what he did to Tamar, but you know he was probably recalling his own sin in that same household. Amnon was a grown young man with his own choices and tastes. His sin and actions were his own. By law he could have been put to death for what he had done to Tamar.
So David's fury against Amnon was short-lived for David had committed a similar sin. (Even as I write this, I can see that the family was a complete mess).
We too need to get angry at the things that are destroying the family (the church, so to speak). Sexual sin, greed, love of things, coldness of heart, and many others are great examples of things we need a righteous anger over. And that's not even to mention the multitude of events outside of the church that we need to become furious over.
Pray that god will give you the fury David had and the passion he had later in life towards God