Re: How often to text
No woman wants to be perceived as a whore; she just broke up with a boyfriend(what I would guess was a semi-long relationship) and then hooked up with you. She obviously isn't ready for commitment of any kind, be it a fwb or a possible boyfriend; and on top of that she obviously regrets what transpired. Not because of you, but of how she is perceived.
I would personally let this one go for now, then touch base in a few weeks. However you won't, because you like this girl, and will probably text her in the next few days.
Rule Number 1: You are not a PUA.