I pretty much agree with what everyone else has written -- i.e., call the cops. But I have a couple comments/questions.
She refused and is now threatening to expose this information to my family, friends and employer and clients unless I have a face to face to discussion with her where she will tell me what I need to do to get this information back.
If this is a woman you dated only once, how is it that she knows your family, friends, employer, and clients? I'm sensing there may be more to this story than you've told us. Did you have a pre-existing, non-dating relationship with her?
Should I tell her that I won't give in to paying money or doing anything sexual and that I will file an injunction against her?
An injunction is a court order. You're free to sue her and file a motion seeking an injunction, but you cannot file an injunction. I have to imagine, however, that, by the time you filed suit and served her and filed and served a motion for the injunction, she'll follow through with her threat (thereby mooting the injunction). While she might not follow through and might give you your phone back, going to the cops is a far easier and less expensive way to achieve the same result.
If I file and she releases the info has she committed a felony or is black mail the only felony here?
I'm curious why you seem to be focused on the existence or non-existence of a felony. Why does it matter to you whether the crime is classified as a felony or misdemeanor?