Hugs, Nancy, this is going to be hard on you. Even working your program fastidiously, you will hardly be able to detach completely from difficult child if she is pregnant. There is a little baby in there that no matter what, your heart will love. The sad news is that the sperm donor is a loser. And difficult child is clueless.
The only real thing you can do at this point, well, once you've had a few days to collect yourself, is to point difficult child in the direction of planned parenthood or another free clinic. PP is not just for abortions. Some don't realize that they also offer prenatal care, very cheap and/or free for those who qualify. It would be a way for difficult child to at the very least acquire information about the stages of growth during her pregnancy as well as prenatal vitamins and, very importantly, provide her with condoms to prevent STD's so the baby is not infected by any on the way out.
Like the others, I'm sorry this has happened at this time and that you're world is being rocked. However, you just never know, this may be the impetus for change in difficult child's life. If it's not, I do pray that you have the strength you will need to help the child, not difficult child, but the innocent child. Hugs~