Bitterness is allowing an offense towards us or disappointments to germinate in our hearts, many times coloring our thoughts and actions both consciously and subconsciously. It is characterized by an unforgiving spirit and generally negative, critical attitudes.
Both bitterness and resentment are sinful and self-defeating. Love dispels them.
Harbored they distroy, destruct and kill(Gal. 5:19,20)