Ephesians 4:31 Let all bitterness, wrath, anger, clamour, and evil speaking be put away from you, with all malice.
In order to be kind to each other we have to aim to set things right first of all; this can be as hard as we want it to be or as simple as this verse says.
Putting aside all of the ill feelings, evil ways, harsh thought, harsh words and setting aside the feelings that have built up from past events will release us to move forward.
It may take us a long time before we have the courage and strength to be able to do this; but with God and through God we can and must try.