Mental harassment by ex girlfriend... Trying to contact ever

Hi, I was in a very short relationship when i was in high school but we broke up as i could not go any further because her parents got to know about our relationship and i did not contact her for 4 years but after 4 years she suddenly calls me( by getting my number by contacting my uncle as she knew his house) and tells me if i do not help her she is going to call media, police and defame my parents... I met her in a public place with some friends at my back and told her i could not help her anyhow as i was going to start my career and she said she would run away from her house...i don't know where she is but I have told everything to my parents that i had not even seen her for years. I filed an FIR in case she does something wrong and changed my number But after another year, she found me on FB and again messaged me and got my mom's number from my uncle by using a fake name that she needed to contact her.. Since then she is messaging and calling my mom that she wanted me to call her as there is something important she wanted to tell me Now i don't know what to do, i have many problems in my life l, my dad is not well, my sister is going to get married and i didn't even touch her because it was a very short period 5 years back...i have all the messages she had sent but what could be the thing she wants to tell me is what putting me in trouble. Please tell me what options do i have and please ask me anything in the comments so that i can explain it