Yes it is. You had a poor role model in your father growing up. You found this older man that filled the role of father that you had envisioned in your head as a little girl. You say he was your best friend when he was sober, but it doesn't sound like he was sober most of the time. Watching our parents interact with each other and the world is our model for how to be. Children who are abused are that much more likely to grow up to be abusers themselves.
When a parent or set of parents brings a child into the world, their lives become forfeit. Everything they do should be for this child. A child needs to learn and be nurtured. If a father needs to choose between getting drunk in front of the TV or playing with his daughter in an effort to help her grow into a stable young woman, what should he choose? The decision you made to be with this man is very much related to the disappointment you feel in your father's lack of control over his own life.