It seems to me that some level of anger is almost a prerequisite for the making of Justice in the world. Anger brings huge amounts of energy that can be used to change things. One angry person can change the opinion of an entire even tempered mob. It wasn't until African-Americans became enraged with the Jim Crow laws and this country took to the streets in protest that major civil rights legislation was enacted. Sometimes it takes one spouse to get angry and dig in their feet and stand their ground before any changes get negotiated in a marriage.
Anger can be a powerful tool for change.
The key is training yourself what to grow angry at. Basically, anger can't be avoided. We all know that. To live in community means we get angry along the way, because things aren't always done exactly the way we would like them to be done. Because people unknowingly say things that hurt us sometimes.