Thank you Caleche. It is a question I have asked myself - I also did some therapy after I lost my husband, and so I also asked the therapist this question.
What I now understand is that it is incredibly hard for a child (at almost any age, but particularly when they are young) to accept that their parents have not been good to them. As a young child, doing that means collapsing your entire emotional universe. (On top of that of course I was on a boat, with no passport, no money and no contact with any of my relations.)
Even as an adult it is hard, both because emotionally you don't want it to be true that your parents are bad parents (I still find myself trying to excuse them) and because there is a huge social pressure for most of us to have good relationships with our parents. Even now I have lots of people who say to me that surely I should be trying to have a relationship with my father (which is an odd question in so many ways, not least that he walked out on me in 2019 having disowned or abandoned me several times previously in my life, while I have never walked away from him).
For me the turning point was writing the book. Until that point I had not really confronted what happened on Wavewalker. Of course I remembered but that is different to reliving it - going back through my diaries and talking to people and really understanding what happened. And I was doing that while seeing my own children every day (who were a similar age) through the eyes of a mother, and realising that all the excuses I kept on making for my parents just didn't work.
But the final step was finding my mother's letter to me, which I mention in the epilogue of Wavewalker. That letter made it clear that whatever I might have done (maybe I was a grumpy teenager: I certainly was very unhappy), how she treated me was something being driven by her mental state, not mine.
So now I feel free. And I do wonder why I took so long - but it is so complicated. Maybe that is one of the big learnings in life - that you have the right to decide who to spend your time with and who to love - and you don't have any obligation to give that time or love to anyone who does not deserve it.