Girls do get desperate these days. It's either that, or she's just looking for some trouble. Thank God you did not accept those pictures or replied something naughty to her, because if you did, she most likely would have called you a Myspace Predator and you would not be on this forum anymore because you'd be too busy trying to find a lawyer.
But it is true. They're crazy. Girls can be b*tches. They get desperate for money, sex, partnership.. and they'd go to such lenghths to go and get what they want. It's sad. But it happens.
Yes you did do the right thing. Any other man would have probably tried to lure her somewhere.. and take it from there.