Remain calm. Freaking out about it only makes you seem suspect.

Talk to a lawyer about defamation and how to proceed.

When asked or approached from someone effected explain, laugh it off and apologize for the inconvenience. Don't harp on it as it makes you seem guilty.

Some people won't believe you. Don't let it faze you. Just understand and move on.

Explain to employers if needed after consulting legal counsel.

Literally talk to a lawyer.

This is against the law in a lot of places. Libel/defamation and in this instance, a case might even be made that it was a form of identity theft.

Just in case it isn't obvious--

You need to get rid of this chick.

This is the kind of crazy bitch that is going to wind up stabbing you in the chest with a steak knife, because she 'heard how you were on the phone with that bitch operator!'

Don't make excuses for her bro. She's a nutcase. This thing she's done to you? That's something nutcases do. Eject.

Re: your personal friends. Now you know which ones were actually friends, so that's a plus. Always good to find the weeds in the garden.

Reputation ruining is the NUMBER ONE method women use when they are scorned.

You need to talk to those girls in person and prove to them that it was not you. You have to really choose your words carefully and be convincing as possible. Also, get a lawyer.

I'd be careful bringing this up to the people she talked to. You did do nothing, so don't act as if you need to make up for something you did not.

When you proactively tell those people what you girlfriend did there are two not so cool signals (remember, that's what people see in your actions, not what you intended):

1. You're insecure and worried about your reputation
2. You're talking bad about your GF

If the topic does not come up one way or another, just don't do anything. When you've got to face the "consequences of what you did online!!!" then be calm and tell that you did not do any of that. You cannot control if they believe what you say, just be confident as anyone telling the truth can be.

Sue her.

LTR? Sounds like u like this type of shit. Marry her, considering shes still not your ex and you still havent pressed charges.

Like everyone else said. Nuke her.

free consultation with lawyer. show them evidence. ask if they will work without a retainer on a percentage of the settlement/verdict.

Talk to a lawyer, provide evidence, and then sue the fuck out of her.