I agree with herbgal.
I also had an abortion. An extremely hard choice, I knew I didnt want kids though, and DEFINITELY was not ready (no finances, no home, no nothing). I don't personally believe abortion is "wrong" but it was a rough choice, and after I did it, there was no doubt in my mind I made the right one.
You need to respect that its her choice, IMO. And SHE needs to respect your moral code, and shouldn't ask you to pay for it.