Acknowledging pain and disappointment helps us move past it. Otherwise, it sits inside us and grows. It can infect many other areas of our lives. In my opinion, it's best to do the work to face it and move past it.
I appreciate the quote about being kind to others. We often have no clue the battles that others are facing or fighting and most of us wouldn't willingly or purposely put more weight on that person if we realized how tough things were for them. They might be barely holding it together and our harsh words could be what push them too far.
It's better to give a kind word and have it rejected than to give a harsh word and have it accepted. - themanwithnoname