I'm working on this right now in therapy. I had a falling out with my father and stepmother a few months ago, and the anger has been almost unbearable. For years I kept it all bottled up, and then it all came surging out after this incident. I've been in therapy for a few months and I'm working on some cognitive behavioral techniques that are helping. On of them is the ABC model, which is helping me reframe my thinking. Here's an explanation and a worksheet that I use to write on or at least think through issues when they arise:
https://www.youtube.com/watch?v=OvgtwMCaIcU
http://www.dupagetherapy.com/uploads/ABC_Worksheet_to_Identify___Dispute_Cognitive_Distortions.docx
An example would be:
Activating Event--my dad lashes out at me about a picture I sent him of my son at camp
Belief--"He's a total asshole. I can't believe he would get upset about something as stupid as a picture I sent. Where the hell does he get off?"
Consequence--I'm furiously angry at him and hurt.
With ABC you work on reframing the belief to something more rational. Instead of the belief above, I'm working on thinking, "He's lashing out because he's scared that our relationship is so broken. He's sad that he's not a bigger part of his grandson's life, and he knows that he really doesn't have the capacity to be a loving father or grandfather."
When I reframe my belief then the consequence is that I feel more compassion than anger. My therapist and I are working on the idea that it's better to feel sad about my relationship than to feel anger. Anger keeps me "stuck" and only tears me apart emotionally. It's going to take a while for me to work through this, as it's been ingrained in me for 42 years. However, I'm feeling healthier and freer than I have in years because i'm working through this.
The other tool that I'm using and highly recommend is mindfulness/meditation. I'm finding that even doing five minutes of meditation each morning and each night has really changed my outlook and helped me to let go of and/or control my anger. Slowly I'm finding that I can get back to feeling peaceful when I practice a specific visualization when I start to thinking obsessively (and angrily) about my father. Here's a meditation that I do regularly, and I can use this visualization whenever I start to feel anxious or upset:
https://www.youtube.com/watch?v=i50ZAs7v9es
Best of luck with this. It's hard to overcome, but I agree with the posters who wrote about the power to claim adulthood, even if childhood had been taken away. I'm tired of allowing this to control my life, and I'm ready to create a different narrative for my relationship with my own child.