Maybe with all his problems and GFGness, he was being the best father he knew how to be. Not that that is necessarily much of a comfort... one of my best friends had an abusive difficult child dad. When she talked to family, especially his older sister, she learned a lot about his family life as a child and how he was abused by his father. Sometimes the GFGness is inherited, sometimes the GFGness is imposed by poor treatment and lack of appropriate parenting. Sometimes its both. And the damage progresses through the generations if we aren't able to stop it.
A brother in law of mine had no proper example of normal family life. His parents sent him to boarding school and in the holidays had a nanny for him. They showed no affection and distanced themselves from their children, as if trying to recreate their idea of British upper class upbringing. As a result, brother in law had no idea of how to be a husband and father. I remember when it was his eldest son's bedtime, he would SHAKE HANDS goodnight with his son. Never a hug, never a kiss. The absurdity of shaking hands with a baby stays with me. I remember asking him why (I was a snot-nosed teen at the time) and was told that it was not manly to kiss and hug, and HIS sons would be raised to be men and not sissies.
His sons are an emotional mess, each one of them. And none of them will have anything to do with their father. Very sad, when this kind of damage passes along the generations. My brother in law was a rotten father, but I still believe he was the best father he knew how to be. it's sad - I describe his fathering in the past tense, even though he is still alive, because he gets zero opportunity these days to do anything in a father role with anybody.
Hugs, hon. It hurts for a while. In some ways, it always will. But the hurt changes and becomes easier.
Marg