Healing Your Inner Parent
Unfortunately, anger or resentment towards parents is never safely left tucked away in the past. Most of the time, the mind and heart stores poisonous emotions that don't disappear or heal on their own. They remain stored in the subconscious with its accompanying toxic feelings when left untreated.
So along the way, the process of "repression" that Freud described breaks down. Your past, unprocessed parental wounds can subconsciously exert total command over your present feelings, thoughts, and behaviors. This can be in the form of addictions, alcoholism, infidelity, rage, mental illness, materialism, criminal behavior, among others. The psychological truth then is, holding on to your past resentments toward your father and/or mother robs you of present-day peace of mind, happiness, and health.
Therapy from your parental wounds first involves healing your "inner parents" before you can heal with your real-life parents. Making peace with your real life parents requires enough internal rehabilitation and stability. That involves learning to give up your resentments, your anger, your annoyance, your desire to punish, and your need to blame your father/mother. After that is done enough, you can become a more loving and nurturing person for the healing of your self and the process of healing your relationship with your parents.