It might. Especially if rather than telling her friends, she posts to a forum somewhere where the defense can find it and save a copy of it.

Then when the court case comes, and the defense has her up on the witness stand, they ask her specific questions, and if any of her answers differ from what was in that forum post (and the comments), they call her on the discrepancy. Even minor differences damage her credibility.

They might even be able to use comments (not made by her) against her.

It might also give the defense detailed information about what exactly she's likely to say in court ... giving them time to prepare for it. (Though I would expect this to not be a big factor too often -- courts don't like surprises, and the prosecution has to share any possibly relevant evidence with the defense.

Now, a r*ape trial would be a criminal trial with a collision usually resulting in a civil trial (if it goes to trial at all), but the same general principal applies. Ultimately, the point is that the forum post will just about never help the poster's case... but it's very likely to hurt it.