I've given up on F2F social interaction

I hope that your decision works out for you. The only thing that I felt compelled to say is that this doesn't really need to be a final decision. Just what works for now. You have family, and 'chosen' which is so lovely. Was there an element of socialising that led you to having them, though? I'm just saying that it doesn't need to be written off forever and ever and ever.

Although we regard each other as father and daughter, we are not blood related. She is my late wife's youngest child. We have known each other since just before she was 10. That's over 40 years.Her birth father was not a good person. He was off the scene  before she was school age. My late wife and I met during my last and longest psych admission. Although there was a large age difference, and difference in background, it was though we were made for each other. Kismet perhaps.

I've not seen my brother or sister since moving to Wiltshire in September 2017.My brother and I do exchange regular emails. My sister and I? Minimal exchange of emails,or Facebook messages. 

This may sound strange. I'm far more able to say 'I love you' to what I call my 'chosen family' than I ever have been to my birth family. From the age of 8 to 18 2/3s of my time was spent at boarding school. From 1981 onwards, till he died last July, I saw my father about once a year, apart from a 2 week visit to see  him and my step mum in 1995. He chose to accept a posting as British consul general to Atlanta  when I was at my lowest ebb. He then chose to take early retirement and remain in the States, rather than become Ambassador to the Gabon etc.

I saw much more of my mother, but her alcoholism/problem drinking didn't always make for a psychologically healthy relationship.

Although we regard each other as father and daughter, we are not blood related. She is my late wife's youngest child. We have known each other since just before she was 10. That's over 40 years.Her birth father was not a good person. He was off the scene  before she was school age. My late wife and I met during my last and longest psych admission. Although there was a large age difference, and difference in background, it was though we were made for each other. Kismet perhaps.

I've not seen my brother or sister since moving to Wiltshire in September 2017.My brother and I do exchange regular emails. My sister and I? Minimal exchange of emails,or Facebook messages. 

This may sound strange. I'm far more able to say 'I love you' to what I call my 'chosen family' than I ever have been to my birth family. From the age of 8 to 18 2/3s of my time was spent at boarding school. From 1981 onwards, till he died last July, I saw my father about once a year, apart from a 2 week visit to see  him and my step mum in 1995. He chose to accept a posting as British consul general to Atlanta  when I was at my lowest ebb. He then chose to take early retirement and remain in the States, rather than become Ambassador to the Gabon etc.

I saw much more of my mother, but her alcoholism/problem drinking didn't always make for a psychologically healthy relationship.