As a preface, I'm Catholic, and this is just my $.02.
I quite enjoyed Brown's novels. I recognize that they are fictional novels though. There are many factual and historical inaccuracies (there are no monks in Opus Dei, incorrect number of glass panes in the pyramid, etc), but these inaccuracies are necessary for the plot line to work.
Brown is a fantastic writer. His books draw you into the story and have great plot twists. The problem is that some people fail to understand that his work is fiction, and is no more true than "The Little Mermaid".
I think people get confused over fiction/reality because Brown uses real places, references real people, and puts his own creative twist on historical events.
The guy who told you he would like to hurt people for seeing the movie is quite obviously not being a good example of Catholic's belief of turning the other cheek and being kind to your enemies.
Had I been there are the time I might have either ignored him or quoted one of the following:
A new command I give you: Love one another. As I have loved you, so you must love one another (John 13:34).
But I tell you who hear me: Love your enemies, do good to those who hate you, bless those who curse you, pray for those who mistreat you (Luke 6:27-28).
Do not repay anyone evil for evil. Be careful to do what is right in the eyes of everybody. If it is possible, as far as it depends on you, live at peace with everyone. Do not take revenge, my friends, but leave room for God's wrath, for it is written: "It is mine to avenge; I will repay," says the Lord. On the contrary: "If your enemy is hungry, feed him; if he is thirsty, give him something to drink. In doing this, you will heap burning coals on his head." Do not be overcome by evil, but overcome evil with good (Romans 12:17-21).
Do not repay evil with evil or insult with insult, but with blessing, because to this you were called so that you may inherit a blessing (1 Peter 3:9).
Anyone who claims to be in the light but hates his brother is still in the darkness. Whoever loves his brother lives in the light, and there is nothing in him to make him stumble (1 John 2:9-10).