I am 17 going on 18 in April 0f 2010! He just turned 26! We have been dating for 6 months! I just found out I'm pregnant! My family is cool with it! Except I haven't told my dad... :( don't know if I well) Can he go to jail for dating me! I need him to be a father because I'm keeping this baby! What's the worst thing that could happen? I live in Southern Illinois! What are the laws around this?

Also live in Illinois depends on if issue is pushed or not. 17 is legal age of consent but if your dad wants to get him in trouble he probably could.

Yes he can go to jail or prison. The age of consent has its limitations. Quite frankly he's a child preditor for what he is doing and can be labeled as such for the rest of his life.
Also by being with you in that way he is guilty of other crimes as well.
How old were you when you got pregnant ?