That weight you are carrying from childhood, the anger and the unforgiveness tied to your mother, is a burden too heavy for you to bear alone. When we hold on to those wounds, they do not stay contained. They seep into our spirit and become bitterness, and that bitterness gnaws away at us from the inside. It hurts you far more than it touches the one it is directed against. The call on your life is not to ignore the wrong, but to release the debt entirely, placing it into the hands of the only Judge who is truly just.
To do this daily, you need a vocabulary for your soul. When you come before the Lord, pray something like this: "Father, I bring this anger from my childhood to You. I confess it has turned into bitterness and a hardened heart. I do not have the strength to let this go, so I ask You to take it. Dissolve the hatred and the resentment in the light of Your mercy. By an act of my will, and in obedience to You, I choose to forgive my mother for the failures and the hurts that have held me captive. Release me from this prison, and let me not brood over these memories anymore."
Repentance, too, is a daily turning. It is not merely feeling sorrow for a sin, but a change of mind that produces a change of direction. You asked for simple prayers of repentance. Let your heart cry out: "Lord, search me and know me. Bring to my mind anything that has grieved Your Spirit. I turn from the bitterness, the wrath, the inner clamor, and the unforgiveness. I do not want to be a tree that bears no fruit. Wash me, and renew a right spirit within me." A genuine repentance does not just weep because it lost a blessing; it weeps because the wrong has offended a holy God, and it is ready to walk away from that wrong.
Remember, we are told to be kind, tenderhearted, and forgiving, just as God for Christ’s sake has forgiven us. The model for this life is placed right in the prayer Jesus taught us: forgive us our trespasses as we forgive those who trespass against us. That is not a mathematical equation of seven times or 490 times; it is a way of life. You go on forgiving because a forgiven heart must be a forgiving heart. Let these words be your daily breath until the sharp edge of that childhood anger is worn smooth by the grace of a God who, when you confess your sin, is faithful and just to forgive and to cleanse you from all unrighteousness.