Wearing the bitterness and resentments can look like a way to get back at the person(s) who hurt us. I will show THEM how they messed up my life, how deep those wounds are that forever altered my life into the pits of hell. “I will show YOU how much I am hurting!! How irrelevant I feel; thrown away like disgusting garbage.” These are conflicting situations. What we may prefer is for the hurter to look back and see the swath of damage they left behind them and then realize the amount of destruction they did and eventually apologize or even make amends so WE can feel whole again.
I think that these abusers have so much pain in their own lives they cannot see or even acknowledge that, or even do not know where to go to find their own healing. So they will look to fill those empty spaces in their lives along with their own bitterness, resentments, pain, irrelevance by hurting other people. They might even turn that pain inward at times by abusing/using drugs and alcohol to management those painful feelings.
NOTE that I am NOT making a case for what they did as a justification for their behaviors. We are all responsible for how we feel and what we do with those feelings and corresponding behaviors. We have free will.
I continued those hurtful behaviors to myself for a long time including emotionally, physically, financially, spiritually and mentally figuring if I continue to recreate the same history, my father would finally see what a mess my life was. I continued to eat that lye with my breakfast. Each day was another day filled with pain, greater resentments, bitterness and more misery. I was stuck in a roller coaster prison and I kept tossing the keys to get out to escape.

It is like a tornado who touches down leaving a swath of destruction then when the tornado leaves. The mess seems so widespread, overwhelming, insurmountable and a lonely road we wonder where do we begin to pick up the pieces to reclaim and reorder our lives?
When I was 22, I had a lucid dream about my father. He was in his kitchen making his cup of morning coffee. He had the teakettle on. I saw him scoop his instant coffee in the cup, pour the boiling water, stir the coffee. Turn around to the refrigerator to grab the milk. Pour the milk into his coffee. Return the milk back to the refrigerator. Stir again. Pick up the cup and walked into the living room. With that, I came to the realization that he had absolutely no clue how he destroyed my life. I saw that all that self-abuse was only continuing to punish me, not him. Not anyone else. It was at that moment I declared that I was going to get on with my life NO MATTER WHAT! Was it an easy transition? No. It was an evolution. Each day forward, I tried to turn that destructive energy into something that moved my life forward. I still had the pain. I began to free myself from that prison where I left the door keys in the hands and choices of the abuser. I took the keys back and no longer depended on my father’s apology and acknowledgement of that inflicted pain. Somehow I knew that waiting for that would continue that pattern of being in prison, for him to use my keys to get me out.
My first marriage was very rocky (another re-creation of the past?). As the addiction progressed, I was told that the recovery could take 4 to 5 times for him to get it. I saw myself at 90 sitting on the porch with him in rocking chairs, still using. I wondered who I would be more angry with, him for not getting it or me for waiting for him. Again, it was another opportunity for me to continue to getting on with my life no matter what.
We get opportunities to move forward with our lives. Helping hands have been extended. I understand it is a big stretch to let go of the past stepping out of that seemingly comfortable prison of ours, even if it is an inch at a time, to reach across for something else, something more colorful and eventual joy at living. It takes more courage to do that then staying in prison.