Just because a post was made from your IP does not prove that a specific person made the post. I'm sure several people have access to that computer, right? You leave yourself logged in, and anyone could have made that post, pretending to be you.
Also, in addition to the problems of proof, the post is hearsay, and inadmissible to be used against you in court.
If the story were true, which of course it's not, then your biggest enemies would be #1 her coming up pregnant and #2 her pissed-off daddy. If you don't run into these two problems, you will be fine. Just be more careful next time.