All very good points, Apple. She most certainly would have admitted it to Michael later if she had made it up, especially during their "reconciliation" in GF3. Although sometimes lies that large are hard to admit, no matter what the circumstances.
Then perhaps it's plot weakness that has me pondering. I would think it wouldn't be easy for Kay to receive an illegal abortion. I would that that any doctor would fear her husband's retribution too much. Just my thoughts, one of those things...