Boy, this thread sure went dead in a hurry. This subject seems to be much easier to discuss in hypothetical than in real, human terms. How to clear a room: admit to having had an illegal abortion.

Possible responses (roughly paraphrased)--
1. You murderer! How could you kill your baby? Just wait till Judgment Day, I know just exactly what God has in store for you and your ilk!
2. I have also (had/ been party to) an abortion. (Possibly followed by some narrative.) (We can always post anonymously if we're feeling a little weak in the knees.)
3. I'm sorry to hear that you had to go through such a thing. Maybe it's better for them to be legal and safe.
4. (The popular choice) Silence.

1&2 are awkward, potentially embarrassing, and even if truthful, best kept under one's hat, it seems.