My bio-dad, walked away from us. The last time I spoke to him, I was 8 and he was getting re-married...so...I say, wow,can I go, he said no...no strangers allowed. At 8 I realized all the stuff I heard my mom say, when I was not supposed to be listening, was true. I decided, at 8, to not speak to him anymore. I never looked back. I do not regret it. He has since died and my step-dad forced me to go to the wake for closure reasons.
My step dad taught me that you can love unconditionally and that biology is not required to be part of the equation. He is the reason that I adopted two children. He is amazing. Bio-dad...not so much.
You need to do what you think is right and what you can live with. My Pop (bio's dad) was the most amazing man. They went above and beyond as they were horrified by their child's behavior. He once asked me to stop carrying the hammer so hard and talk to my bio-dad. I told him no. He also agreed that Eddie walking away from me was the best thing that he could have done as he was selfish and all about him.
My 3 kids have the most amazing grand-pop. Not only did my step dad raise me as his own, he is 150% all grandpop. All of us are quite lucky to have him.