Hello! So, I'm going to try to summarize this as much as I can. (I'm on mobile so sorry for formatting)
My mother had an affair with a man and got pregnant with me. At the time, my bio dad asked her if I was his and she said no, and he left it at that and they lost contact. My mom continues having an affair with other men and eventually my dad (the man who raised me) found out and they got divorced. When I turned 33, I took a DNA test for fun and found out I wasn't related to the man that I thought was my father. About a year later I met my bio dad and we have been talking but...I feel some resentment towards him for not trying harder to find out if I was his or not. I know my mom is largely to blame for the deception obviously, but I guess I just wanted him to take accountability for the affair and maybe even just "sorry I wasn't able to be in your life".
But is that an unfair expectation? He basically just shrugs and says "what was I supposed to do?"