Married then Divorced

I got married young at 18 I had gotten my girlfriend pregnant, and we were married 8 years and then we divorced. My son was 7 and my ex-wife decided I should have custody of him, she had always seemed detached from him. But during the marriage I put it down to her university studies distracting her. I also was university and graduated a year ahead of my wife. With the divorce complete my ex-wife moved away and so far, hasn't come to see our son again or contact him in 11 years since she left. I was left to raise my son and had the help of my mother widow and younger sister. I was well off due trust fund and great job, even after a one-off divorce payment to my ex-wife. As I have custody of my son, she cannot make any more claims against me and cannot try and take him away from me either as she showed no interest in him at all. After the divorce my sister who was at university studying art help our mother care for my son. My mother wasn't very well at the best of times (cancer 2018). It would claim her 4 years later, now alone with my sister and my son we continued as a family unit. Some people thought us married and we didn't correct them. Then 2020 and the pandemic and my sister and I started sharing my bed and having regular sex and she got pregnant and had our daughter 2021 and just had our son April 2023. She wears our late mother's wedding rings and is called Mom by her nephew my first son. With our children all healthy, we act as a married couple and have no other relationships. It works for us.