The full verse of Eph. 4:26: In your anger do not sin”: Do not let the sun go down while you are still angry,”
Anger is an emotion, and our emotions are good and healthy to experience. What makes the difference is what we do with that emotion. If someone cuts you off on the freeway, do you flip them off? If someone pushes you around unnecessarily at the club, do you punch them? Someone insults you, do you gossip, back talk, talk bad, slander them?
Do something about it; make amends, or move on. Don’t dwell on it and fume. Also, do not take on the full responsibility of their actions (don’t you be the one to constantly apologize or go to Confession for it). Was the cause of the anger, something significant? Does a compromise need to be reached? Does someone need to be taken down a notch? Would some time away be wise?
An example in my own life: I cut off one friend and deleted all his contact information because I told him I wasn’t going to stand for one more abusive 2am drunken phone call. I would be there if he needed help, but if all he wanted to do was to cuss me out, I wasn’t going to stick around for that. And I haven’t. Another person told me that I should not speak until I was spoken to; to not offer an opinion or thought unless it was specifically asked of me. Words were exchanged and I decided that I wasn’t going to speak to this person until they spoke to me. I haven’t spoken to him since: I deleted his email phone number etc – why bother? Its not the 1800s and the original instigation of this ‘rule’ was something that I was perfectly justified in saying (I’ve gone to Confession time and again for it, I’ve spoken to so many priests about it) why should I have to keep apologizing for it? I don’t! I’ve let it go. Anyone who makes demands on me to keep quiet, without proper reason, when they themselves cannot follow propriety themselves is not a person I’ll be acquainted with.