Well, first, I want to apologize for sounding harsh.
I know how hard it is to let go, particularly due to what you've gone thru. I'm sorry you had to have an abortion. Are there any resources you can seek out for counseling? I think you would benefit from it ( I don't often recommend therapy). You are clinging to the idea of this man, the "what ifs," and how you want/hoped he would care. He doesn't. He doesn't even want you on his FB page. In truth, this man was just a sperm donor. The unfortunate exp you've had was a result of the reproductive element of sex. That's all it was, harsh as it sounds. You will do yourself a great favor by turning your back on the man.
You need to concentrate on yourself now. That really IS the only thing that matters at this point....not him at all , ever. You will feel such pride and sense of worth by letting go of any thoughts of the man. You can embark on a new chapter of your own precious life right now by focusing on your own health and emotional well-being.