TS, you made a mistake and I think you have paid enough for it.
Here's my advice. You have to let her know that you don't have
money and cannot afford to pay her anymore money. Reason being, she
will keep sucking on you until you're 60 years old, can you really
afford that? Imagine one day you get married to the girl of your
dreams, and she will come threaten you, are you going to live your
life in the darkness forever?
I suggest totally ignore her, if you need to change contact
information, then do your best to change.
Let her know that what she is doing is extortion and it's also
not a good thing to do, but best is to resolve the issue without
bringing the matter to court. Issue being, if the girl wants to go
all out war, she can lie to the police. In Singapore, it's a
pro-female country. For example, even if the wife has affairs and
caused the marriage to end, the guy still need to give the wife
alimony, it's very unfair. By lying to the police, it's a criminal
offence but then that's assuming the police have evidence
to catch her lies, otherwise it will just be my story vs your
story. Like I say, Singapore is a pro-female country with laws
bias on the side for the ladies.
Hope you solve this problem asap, the way i see it, it's a huge
burden on your life.