Gavin de Becker wrote an excellent bookj called "The Gift Of Fear". Among other things it deals with stalking.
He explains very, very well that for every once that you communicate back, you will get six more messages pestering you. The suggestion that you text her with a polite brush-off is a good one - I'm just saying you should be prepared for - and be prepared to permanently ignore - six at the very least.
Remember, you will have to make the decision to ignore every single text message or call that you get from her from now on. Absolutely any response after your first "no" will be taken as encouragement, no matter how what its content. (The medium IS the message; negative attention is still attention.) It's good that you contacted head basket weaver.
And don't worry about it: it really is a case of least said soonest mended. The hardest thing is to just not respond. No matter how you gnash your teeth or tear your hair - make a commitment to yourself of nonresponsiveness. Be prepared for an ambush of needing-helped (seems she's pegged you as a softie!) and stand firm. On the plus side, you learn a helluva lot about human nature from this: there's a small minority of people everywhere who are like this, and they cause psychological and social mayhem everywhere they go. In the end, they are their own worst enemies: they scheme and lie and betray trust routinely, and this of course means that they can never trust or truly be friends with anyone. They're lonely people - but that is for them to deal with, not you.
Meantime, every time your phone goes (set it to silent; or block her number) congratulate yourself on your canny instincts. You'll spot the next con-artist at a distance, believe me!
And next time you ride your bike, think of how amazingly uncommon these people are (one or two in a hundred, fewer still as extreme as this one) and how genuinely good-hearted most people are most of the time.
