no one is necessarily in trouble for posting info about Karen---if she did put this info into the public domain.
The tort would come if you, say, posted her address or phone number somewhere, misrepresented her as a prostitute and she was bothered by people looking for her in this capacity (that actually happened in California---Gary Dellapenta did something like this to a neighbor and was tried and convicted under California Civil Code 1708.7---just search "Dellapenta---there was plenty of press on it)
The tort in the present case would come if you falsely listed the other woman's (Karen Austin) phone number here as the Karen you thought she was and she suffered emotional distress by getting a bunch of harassing phone calls, AS A RESULT OF YOUR ACTION. Then, no question, I think you're in for money damages, dont know about criminal penalties. As I understand it, Texas has a Cyberstalking task force that works with the FBI to locate "anonymous" posters.