When was the last time that you were mistreated by people or a certain person? Were you hurt? Absolutely, it can really be hurtful if people mistreats us. But, take heart and be patient with them. Do not curse them. Instead, bless them with powerful words that comes from God.
Indeed, it is really hard to do this. This can be a heavy task in our hearts. But, God commanded us in Romans 12:14 that we should ask Him from our hearts to bless our everyone who mistreats us. Ask Him to bless them and not to curse them. Extend grace and still show them the love that comes from God.
Vengeance is not ours, it is God's. Forgive those people with all your heart and live in peace. Your life will be peaceful if you will just surrender this concern to the Lord. He will take care of this. He will bless the people who will speak blessings to each other and He will put a curse on anyone who puts a curse on each other (Gen. 12:3)