I'm going to snap at my fiance's aunt
Why are you upset with her aunt?
She has insulted me.
If you have a conflict in your family you should try to keep the peace. You should talk to her in private and not make a scene.
Nah, I think I'll just be super passive aggressive with her. That's more my style.
It sounds like you are trying to start trouble and I'm not sure why. Aren't you worried that being rude to your fiance's family will upset her? Can't you just ignore the aunt?