A gentle answer turns away wrath, but a harsh word stirs up anger. - Proverbs 15:1

If your brother sins against you, go and tell him his fault, between you and him alone. If he listens to you, you have gained your brother. - Matthew 18:15

It doesn't matter if they apologized. Forgive them anyways.

Let us therefore make every effort to do what leads to peace and to mutual edification. - Romans 14:19