My former classmate has been very salty and cold at me? I did nothing wrong.

So I saw me of my former classmate and I went over and said hi went to hug her but she moved back and gave me a snarky look.
I was like, “Oh wow Is like that now? Okay.”
She walked away. So I followed after her and said, “What was that for?”
She gave me a look and said, “Oh NOW you want to talk to me?! Are you dense?! I don’t wanna talk to you and you know why!”
And she walked off. I’m so shocked at her behavior. I didn’t do anything wrong.
I told my friend about it and she said maybe I did something to hurt her and I’m too stuck up to admit it. I got confused. Then she said, “Look I know your reputation according to your sister, of hurting others so maybe you did something to her.”