barrow money in abroad

hello im working here in israel and i have 1 cousin here she beg me to help her she barrow money on me $5000 last September 2011 and she promise me that she will pay me $500 every month starting January 2012.and she also wrote a letter proof that she will pay me.In the letter she mension that she will pay me here in Israel OR even in the phillipines in case of if I decided to stay in the phillipines..But its been 11 months that she didnt pay me and also she ignore me.Im still here in israel and im planning to go back in the phillipines thats why I really need my money...But she refuse to talk to me.Can I sue her? becouse she lie to me and she ignore our agreement.thank you and hoping for you responce.God Bless you.