Honestly, I wouldn’t call that woman your mother. She didn’t raise you at all. She killed a baby and put you in their place, and let others do all the work in raising you. At best, she’s just your stalker that you happen to share DNA with.

I’m not sure how I would react if I was your dad. He’s not in a good mental state from what I’ve gleaned. I recommend therapy and counselling for you both. The best scenario is that he continues to love and care for you as he always has, he did stay with you and raise you despite his family saying to leave. But, I understand why you don’t want to face him. Best not to push the envelope.

As for answers, did she have any electronics? Maybe she kept notes on there, or she kept a diary. You can also check to see if she had any relatives or friends that might have some insight.