First of all, sorry to be hearing this.
Well, most of the responds I saw thinks that the way she is
behaving is being "lok".
But I think there's more to that. Who likes to have a reputation
damaged, not to mention its a girl, which is most important to her.
Even for girls who work in postitution centres, I don't think that
when they are young, they dreamed of becoming prostitudes. Most of
the time its circumtances which forced people to do things which
they never intended to. For example, for three meals a day?
Well, for your situation, your ex-girlfriend may have suffered
blows emotional, which has made her lose her interest in life, not
to mention reputation. Family problems may contribute greatly to
that, or maybe its because she wants to spite you and make you
jealous, cause she can't forget you, and hopes to see you care for
her again? It's hard to say what is happening, and its even harder
to read a girl's mind. But from my point of view, no girl wants to
be "lok" in nature. When someone suffers from heavy emotional
blows, and loses his/her interest in life anymore, I don't think
she would even be rational about things going on around her, would
she even think so much as to what she is doing? her
reputation?
I think the best way is to talk to her, show her some concern, show
her that even though that you may have broken up with her, you
still care for her even as a friend. Ask for your current
girlfriend for her understanding on this, as you would not want to
be caught in between.
Ps: I'm relativly new here, and do not know much about any of you
guys. But this is just my 2 cents worth. Hope I had not offended
anyone of you guys here with my comments. 
[This message has been edited by N|rVaNa07 (edited 09 October
2001).]