WOW! I agree with everyone, red flag, RUN! He's not right at all. Not only is his method twisted, perverted (all of the above) he wants to teach it at eight years old, she'll still be a baby she doesn't need to be learning all that at 8. I wouldn't force the issue on any child, and only explain if the child starts asking questions. My son started asking question (where do babies come from) at a young age. They'll ask that at five years old, but you've got to explain it in age appropriate ways. I wouldn't use pictures for an eight year old. My son is 11 and I wouldn't show him pictures yet. I don't think I'd ever feel comfortable showing my children nude pictures of adults that's sick, that's why they make diagrams and teach it in school.
Your instincts are right, trust them, if he's offering you an out, take it and run. Otherwise you will allways worry.

Take care of yourself and that baby!