Have her take the morning after pill. Good for up to 3 days after an "accident". I think the number is 1-800-not2late and they can help you find a place to get it. It most likely WILL make her sick somewhat (feeling blah/pukey) but nothing serious. She may have to go get it herself as guys usually aren't allowed to receive it. Don't wait around for something you both aren't ready for.
If she has BC pill, or a friend does, Have her take a double dose which SHOULD act as a rejection agent.
3 out of 2 people have problems with fractions.