Would this make you mad?

I innocently expressed my opinion about this girl Karla my fiance is friends with ( I don't like Karla, and she is all over my fiance all the time.) And my fiance (shes a girl as well :P) got all mad and said I shouldn't judge people whom I don't know.... I'm not even allowed to express my opinion anymore? My fiance expects me to be nice to Karla just because shes her friend... I don't have to like everyone, right?