Ah so many good points. Thank you everyone.

Cinnamon - as is so often the case, your insightful post has been really helpful. Yes. Being seen. That's what was new about this situation and that's where the shame spiral began. It makes me wonder about early messages that if my pain and my needs are seen, I will be thought less of. I know my biggest fear here is that he will think less of me somehow. That he won't like me anymore. For some reason it feels of paramount importance to protect his positive feelings towards me. I suspect this relates to my mother, whose unstable mental health became such a source of frustration for my father that my mother left the family home when I was 5. I think I rejected her on some level too. I saw her mental health issues as something that made her lesser. Although my father never said anything like that to me, I think that is how I interpreted the divorce. That she should be rejected.
Of course, as an adult I don't feel that way at all but somehow I expect the same rejection from others. I think I am left with what I must have felt when I saw my mother rejected by my father - "I must never show such weakness or neediness or my father will reject me too".
Damn. There's a realisation.