GF said I try to hurt her sister

I heard my(15m) long distance gf(16f) and her little sister(8f) speaking on how little sis is getting bullied at school. I could be a victim to bully if I didnt know what to do as kids have threatened me and tried to nab at me before. This was the first time she speaked up so I began trying to give my advice. Things such as try to make your bubble bigger because those kids just want to put you lower so they feel high and invite them to your seat becuase they wont know how to react if invited by the one they pick on. She said I’m trying to get her sister hurt and bullied and it really hurt me. I dont know how to respond. She said my advice sucks.

Tldr : tried giving gf little sister advice on bullys and she said I’m trying to hurt her