Dear friend,
bearing with one another, and forgiving each other, if any man has a complaint against any; even as Christ forgave you, so you also do.
Working through forgiveness is not a single decision made once and finished, whatever the language around it suggests. It tends to be a debt you keep being asked to reconsider, sometimes in the same afternoon.
Paul wrote to the Colossians about bearing with one another and forgiving as the Lord forgave them, and I notice he does not say the feeling has to arrive first, or that the other person has to earn it, or that the account gets settled and closed for good. He names it as something ongoing, done again as needed, the way you keep paying down something large in smaller amounts. That has always struck me as more honest than the version where forgiveness is one clean transaction.
Here is one small thing to consider, small enough to finish before bed: writing the person's name on a card, and beneath it one sentence about what you are choosing to release tonight, not everything, just tonight's portion, then leaving the card somewhere you will see it in the morning. I have done this when the weight seemed too large to move all at once. It did not empty the debt. It marked a payment. Would naming just tonight's portion make the whole weight easier to lift tomorrow?
A prayer
God, You know the debt she has been carrying and how long the accounting has gone on. Give her the strength for tonight's small release, and meet her again in the morning with what remains. Amen.