Has she had any kind of counseling at all on this? other than talking to you, and, nothing personal, you are not a trained professional.
Planned parenthood, while this is unplanned, might have some resources for her, or at least get her pre-natal care, so she has a healthy baby
http://www.ppnt.org/default.asp?pageid=280
I am also having a tough time with this 26 year old, who's guilty of statutory rape. If she does keep the baby, I'd go for a paternity test right away, he's on the hook for child support for the next 18 years, whether or not they marry - -whether she can collect it is another story, but she doesn't need to marry him to get that support.