curse

My 2 cents:

Cursing is like a gun, Never point it at something you don't intend to kill. Do you want to kill her?

The three fold rule, if you cast it on her, something will happen to you three times as bad

Just my opinion but just ignore her and try to find better friends.
If I would curse everyone who makes fun of me, talks behind my back or stuff like that I wouldn't have much people walking around me here, 'cuz I'm kind of a target around here.
If they don't want me fine, there are other people to chat with and it's not like I need them..
You don't need that kind of person around you so just find other and better friends, it's a big world, 6 miljard people so there has to be someone around right ^^
hope you become happy
grtz