Please help me help my daughter !!?

My daughter is 20 yrs old. She found out she was pregnant last Dec 09 and thought she had gotten pregnant by her long time boyfriend. Her and her boyfriend had broken up for about 6 months, and she had been seeing another guy, but after the 6 months she realized she still loved her old boyfriend and they got back together. Because she was on NUVARING all along, when she found out she was pregnant, she umed she was pregnant by her long time boyfriend. She bought clothes for the baby, picked a name and was very excited... But 3 weeks ago, during a sonogram she was informed that she was much further along than expected, and it turns out the baby is NOT her boyfriends but her ex. She is now 5 months pregnant and her long time boyfriend dumped her afetr realizing the baby is not his. She is now decided to abort next week!! I am heart broken because she is so far into the pregnancy. She has had a sonogram picture on my refrigerator, We have shopped for clothing for the baby boy. She changed her mind about having him because her boyfriend does not want the baby, but he is now seeing someone else. I think she will regret having an abortion this far into it. I do not know what to do. She lives in my house and we support her financially. I am so angry I want to tell her to move out. I do not want to be around her when she kills this baby. Please do not comment about the religious aspect of this... she is atheist.