I discovered the family secret

My mother Tina was widowed when I was 12 and my brother John was 14, we had to move in with our mother's brother David. David was quiet and kept to himself quite a bit and would go away for work, that's what we were told. He lived 12 miles outside of the nearest town and as Tina's younger brother and only sibling, he turned to him for help as their parents had already passed away. My father John had no family we knew of and he hadn't ever mentioned other than his late parents, so Tina turned to David on his death (car accident). Tina got pregnant when I was 14 and I got a sister Kate, I didn't know who the father was and wasn't really interested at the time. At 17 Tina had another child a boy she called David, it was after his birth I got interested in who the father was. My brother John went off to university and I wasn't good enough at my studies to follow him. He done well and got a great job after university and stayed in the city, our mother got ill (cancer) and passed away at 47 when I was 26. With Kate only 12 almost 13 and David 9 going on 10, I was needed to take care of them. I was still living at home and had been looking after Tina while was ill and taking care of my younger siblings. I stayed at home doing the housework and cooking, uncle David still when away working and I still don't know what it is he does. But While packing away Tina's things I found her journal, not a diary it wasn't her daily life story just every month or so. I started looking to find who Kate and David's father was, I found out it was David her brother and they had started almost the same time we moved in after my father's death.
It wasn't as big a surprise to me as I thought would be. But I now know and quite happy Tina was very happy with David as her lover. Also he is mine now also.