Ice doesn’t melt all at once. It goes drop by drop. So does a grudge if you let it.

Forgiveness is rarely a decision you make once. It happens slowly and unevenly, with days where you feel fine and days where the whole thing returns, and that is not a sign you failed at it. The hardness goes a drop at a time, mostly during the periods when you are not working on it. You cannot force a melt, only stop refreezing it.

Try leaving the story untold for a while and see what happens to the temperature. You do not have to decide to forgive anybody today. If it is still solid in a year, that is worth talking through with somebody rather than carrying alone.