I was very annoyed that he had called me his daughter. I just wonder why he wants contact now, after all this time. But that is all I wonder about & I can certainly live without knowing why if he leaves me alone.
Yes, I don't blame you being annoyed, it's outrageous and particularly when said to an outsider. He is interfering in your life and isn't even keeping this confidential. You have the right for your origins not to be broadcast to neighbours or strangers.
This stuff is all personal and it's completely your prerogative to do what you want. The people that have said you owe him nothing are right.
Fwiw, I have a little experience of these things but from another perspective. Found out two years ago that my mum had twin daughters nine years before I was born and put them up for adoption. They contacted her after nearly fifty years. They had already mourned their adoptive parents who they loved and who had always made clear to them that they wouldn't mind if they sought their biological parents. Then they looked for my mum.
My mum really did think about them every day for 48 years. But she gave birth to them and had them with her for six weeks. She wanted desperately to keep them but when their father wouldn't marry her, she couldn't.
She was thrilled when they got in touch. But she always saw it as their prerogative and would never have dreamt of seeking a relationship with them against their wishes or even contacting them. She actually saw their failure to look for her as comforting, because she thought it meant they were happy with their lives.
It was a bit tricky at first, mostly because mum had never told my three siblings and me about what happened and it was a shock, but we all love each other and it's worked out well.
Now they are about to meet their natural father. I know my mum finds this a little difficult because she feels he doesn't deserve these wonderful women in his life (he denied paternity at the time, which led directly to their adoption), but she is pleased for them because they want to meet him. The point is, it is their choice.
If you really have any respect for your natural children you do not seek to impose yourself on them. He didn't take any responsibility for you then, and now he is making demands. If you want nothing from him tell him to fuck off and get the law behind you if necessary.
Also, really sorry about your dad. It must be even harder for you having this man come into your life when your real dad is ill. Hope all goes well with his treatment.