Underage being traped and later defamed

Hi sir/ma'am I'm from Bangalore. I'm currently 18 years old but when this story started I was 16. A 25 year old woman(now 26) has been liking me since almost 18 months. She tried multiple times to talk to me in the gym but I never responded. After about 5 -6 times of her trying to do so I decided to say hi. I spoke to her and told her my age and she felt embarrassed. But gave me her number. We exchanged few texts had a conflict later she blocked me. Then after that she unblocked after few weeks and came to the gym in my timings purposely and coming near me etc etc.. I still didn't respond. She stoped. After 2 months I randomly texted her again. She blocked and told me she can talk face to face. We spoke for a few days. Later after Christmas vacation I avoided her again as I felt unsafe because of her not unblocking me. Then 1 month later tried talking again she got angry shouted at me infront of everyone and told me she's engaged and soon to be married. She lied that she got engaged during Christmas vacation. Truth I found out later is she's been dating her boyfriend from long time. When I found out she got scared and told her family and friends that I'm following her and troubling her. Her boyfriend doesn't live in Bangalore. He came here and went to the community gym and asked about me and told the trainers to keep me away or else he'll give police complaint. Trainers being trainers spreaded this to a few of their clients. This happened a week before my board exams. She even now lies about me to her fiance and friends and family. I get weird looks and stared from people in my apartment. She has 1 friend who was helping her in this when she liked me. I would like to tell my family and file a defamation case on her.