My wife and kids moved in with my best friend. Each of these five single-again Christians believed their marriage would last forever. They were all wrong. They were all angry. One out of four married adults will experience divorce.
Anger is a natural response.
And just as accepting Christ does not guarantee a lifelong marriage, neither does it guarantee freedom from rage. As a Christian, you have even more to process than anger because you also feel guilty about breaking a sacred covenant. I know the feeling. I'm a Christian. I, too, believed marriage would last forever.