And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you. - Eph 4:32
It could be difficult to let go offences but it's not impossible. Most times the question is not whether we can forgive but whether we will forgive. True forgiveness flows from the heart and not from the mouth. Why? It wasn't the mouth that gets hurt but the heart.
When a man is hurt by another, a cut is being made on the heart of the recipient of the hurt. If he uncovers it without treating it with the gentle grease of patience and love, he allows bitterness to worsen the state of the hurt.
Bitterness of heart leads to hatred, which produces hunger lending to shed blood. If you can't forgive others here on earth, be assured God will not welcome cases of resolving unforgiveness in heaven. He will rather reward forgivers who in spite of their hurt counted it not against others but took it as part of the losses and sufferings for Christ. So, watch it! Forgive that man, woman, boy or girl who you are holding deep down in your heart with bitterness.
May you receive the grace never to house offences in your heart, so you could experience the refreshing of your soul that comes from forgiveness, in Jesus name.