Like you, Sheila, I have lived in Germany for over 40 years. I only have a sister in the UK now and some cousins who I only really exchange Christmas cards with.
I do get homesick a little, and wonder if I would go back if my husband died.
In the 70s I was busy growing up and settling in. In the 80s I was busy with bringing up children. In the 90s I threw myself into work and trying to do it all, so there wasn't much time for anything else.
Then along came the Internet and I could keep up with things in the UK, listen to Radio 4 and 3, so homesickness was alleviated somewhat.
I also have a lovely group of friends from all over Britain. We haven't been able to meet up this year but have been in regular contact in our WhatsApp group.
We have all now taken on German nationality, except those from NI who got Irish passports.
You have 2 homes now, so, if you can't go back, can you somehow make your home here more bearable by finding other Brits or any English-speaking expats. There must be loads in Berlin.
My DS3 is studying in Berlin,by the way. We haven't managed to get out there the whole time he's been there. Hope to make the effort this year before he leaves!