How to find the words for the suffering, the deep-down and intense sense of unworthiness and failure, when one's parent are rejecting and abusive?

At the level of logic, you know that you have value to others. A the level of logic, you know you have achieved well. At the level of practicality, you have searchedout and created family-like structures around you, including here at PC. I admire your skill, resourcefulness, and resilience in doing these things. Time, therapy, support, and separation will go a verylong ways towards salving the pain and healing the wounds. Hang in there and keep seeking out health-promoting people and support!