It is hard to forgive someone who did not repent. It is hard to understand even why we should. In fact, some who have wronged us are happy to have wronged us and are not looking to be forgiven.
We need to learn a new and biblical word for forgive. That word is “release.” Yes, the Greek word _aphiemi_ can mean forgive, but only as an extension of its real meaning, release (see https://studybible.info/strongs/G863). Thus, in Matthew 6, Jesus teaches us to pray (more correctly translated), “Release us from our debts, just as we release the ones indebted to us.” After Jesus teaches the prayer, he then says, “If you do not release men from their trespasses, neither will your Heavenly Father release you from your trespasses.”
“Trespass” is a really cool Greek word that is literally “sidestep.” I think it can carry the meaning of “I really didn’t mean to slip into that” (see https://studybible.info/strongs/G3900). Either way, with both debts and someone that has trespassed (think, on your land), you can release them without forgiving them in the English sense of the word. Forgiving a debt does not mean you feel bettter about having lost the money. It means telling the person that they don’t have to pay you back. (If you are prone to not forgiving debts, you MUST read the parable of the unforgiving steward in Matthew 18:23-35.)
It is the same with someone trespassing on your property. You may have a sign saying “trespassers will be shot,” and you may be really angry, but in most cases people are satisfied not to shoot trespassers, but just to run them off. They have “released” the person from the trespass even if they have not forgiven them in the normal sense of the word.
I think this an important concept. Even though we have offended God much worse than others have offended us, God is kind toward us, always offering us release. He offers not to punish us at all if we will repent.
He will only do this, however, if we do this for others, and it is something we can do! It’s okay if you’re still angry. You can release those who have offended you from your wrath and from your retaliation. You may still feel bad, but you will have pleased God, and I’ll bet he will go right to work on your feelings. You also won’t feel stupid for forgiving someone who doesn’t care about being forgiven anyway, or who may deny that there is anything to be forgive for. What Jesus is getting at is that just as the Father has released you from the punishment for your many transgressions, you must release others from punishment for their few transgressions against you. Stop praying against them and pray for them. You may still have to stay away from them because they are evil or a bad influence or simply because they suck the life out of you, but you can pray they be released from all punishment from you or from God.
I hope that’s clear. I get asked all the time about how to forgive someone who does not want to be forgiven. Think release, not forgiveness.