You can put an end to those kinds of failures in the future by basing your forgiveness on Faith rather than feelings. True forgiveness does not have anything to do with how we feel. It's an act of the will and is based on obedience to God and on Faith in Him.
We are to forgive others as God forgives us (Eph. 4:32). To release others from guilt permanently and unconditionally we are to purposely refuse to keep record of the wrongs that we have suffered.
As we do that, something supernatural will happen within us. The pain once caused by that incident will disappear. The power of God will wash away the effects of it and we'll be able to leave it behind us once and for all. Listen to Kevin Levar as he sings "I want a heart that forgives."
When we forgive others we receive God's healing. Therefore, "Let all bitterness, and wrath, and anger, and clamour, and evil speaking, be put away from you, with all malice: And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you" (Ephesian 4:31-32). Let it GO! Yes let it Go.