IMO I would stick with the girl, fuck it... even if you leave her you're going to see her forever because of the baby, so might as well make the best of it and stay with her.
Try to be nice, just think before you act and don't freak out... try asking for the cribs and shit... I am sure you can do it....
BTW go watch Juno, good movie. [not being sarcastic/rude]