You really think she is a "murderess"? Society never has, by any punishments legislated toward the woman when abortion was illegal (i.e., none). By your logic, any murderer could say, "I'm really, really, sorry", and that would be the end of it.
Let me jump in for a bit, since I clearly lived through the founding of that non-existant "Constitutional right". Yes, a murderer CAN say "I'm truly, truly sorry", however, that won't (or shouldn't) exempt him from punishment.
A woman may be forgiven by God providing her repentance is truly of/from the heart (only God knows that for sure) but there still will be consequences, not by an eartly court perhaps but by conscience. I don't believe that can be argued, really. It could be that that punishment (conscience) is far more severe.