Again someone sent me mean messages on Instagram. Why does it happen to me?

I have shared previously that some dude on Instagram was sending me mean messages calling me ugly and bragging about the girls he had fun with and how his social life is better than mine. I ended up blocking him after he started annoying me by video calling me. Then he had again tried video calling me using his another Instagram account which I blocked again and then things had been good for weeks until yesterday again someone messaged me and this time it was a girl but she didn't have any profile pic or followers and she says its her alt account which she uses to chat with strangers. She said she is 19 almost 20 and I am 21 and was flattered that a girl messaged me first. She was also kinda flirting with me. We are both in different cities of India. Yeah she is from Delhi and I am in Bangalore. She even sent me kissing emojis and I was flattered and said her thanks. But next day she deleted all those conversations and asked me who are you. I was confused and said about all the chats she did with me. And then she said she was drunk and slowly we began chatting and her replies got meaner. She started saying how weird and ugly I look and said how much of a loser I am as I still don't have a girlfriend even at 21. Her replies were similar to that guy's replies whom I had blocked and I am sure its that guy himself with another account but this time pretending to be a girl to belittle me. She also said she would have been my girlfriend if I was good-looking. I got angry and told her to f*ck off. Then she called me a loser for saying like that to a girl and threatened me that if I give her rude replies, she will tell her boys to go to my city and beat me up. Then she started bragging how many boyfriends she had and how I have no chance of getting a girlfriend. I got angry and insulted back. Then at one point she replied "Shut up you vagdevi pooop smeller". Thats when I felt confirmed that its that guy or one of my bullies from my school days because vagdevi was the school where I studied and also no way would someone who lives in a different city knows about which school I went and that guy was calling me that before I blocked him. Then she said how famous I am in entire India and how everyone laughs at my Instagram posts. At last that person offline. I was so angry.