Lets make thing clear first, is she spreading hearsays about you? is that what you mean in your statement that he/she is defaming your name?
yu can file a case for slander/oral defamation
Under the Revised Penal Code of the Philippines, Slander or Oral defamation is punished as follows:
“Art. 358. Slander. — Oral defamation shall be punished by arresto mayor in its maximum period to prision correccional in its minimum period if it is of a serious and insulting nature; otherwise the penalty shall be arresto menor or a fine not exceeding 200 pesos”.
In the case of Daniel Victorio and Exequiel Victorio vs. The Hon. Court of Appeals and The People of the Philippines (G.R. Nos. L-32836-37 May 3, 1989), the Supreme Court defined slander as follows:
“The term oral defamation or slander as now understood, has been defined as the speaking of base and defamatory words which tend to prejudice another in his reputation, office, trade, business or means of livelihood”
In your case, Im assuming that she is circulating to your barangay that you are a prostitute is seriously a degaring remark, it would amount to grave oral defamation which could impose her the higher penalty.