Hate no one, no matter how much they’ve wronged you. Live humbly, no matter how wealthy you become. Think positively, no matter how hard life is. Give, even if you’ve been given little. Keep in touch with the ones who have forgotten you, and forgive those who have wronged you; And do not stop praying for the best for those you love - Imam Ali ibn Abi Taleb

I'm angry. They wronged me, why should I forgive them?
They lied, they cheated, why should I forgive them?

Forgiveness is not a reprieve or a gift that we give to someone else.
Forgiveness for another's act or omission is a reprieve and gift that we give ourself. We are the one who suffers the upset and the anger when we feel that we have been wronged. It is our own blood pressure that rises when we hold on to resentment.

Give yourself the gift of forgiving others, not because "they" deserve it, but because you deserve the serenity and joy that comes from releasing resentment and anger, and from embracing universal forgiveness.

Not a day goes by where someone somewhere says something to upset us or hurt us. Many a time we harbor hate and anger against that person and don't even think about forgiving them, yet Allah tells us in the Qur'an

"Pardon them and overlook - Allah loves those who do good" (Qur'an 5:13)

"Those who control their anger and are forgiving towards people; Allah loves the good." (Qur'an, 3: 134)

The good deed and the evil deed cannot be equal. Repel (the evil) with one which is better (i.e. Allâh ordered the faithful believers to be patient at the time of anger, and to excuse those who treat them badly), then verily! he, between whom and you there was enmity, (will become) as though he was a close friend.

But none is granted it (the above quality) except those who are patient, and none is granted it except the owner of the great portion (of the happiness in the Hereafter i.e. Paradise and in this world of a high moral character).
(Qur'an 41:34-35)~