Go ballistic
Get very angry, such that you lose your self-control.
I wouldn't start by telling her that you actually slept with Rachel. She'd go ballistic and you'd never be able to explain the rest.
going ballistic
Becoming fully, truly, unstoppably, gravitationally angry. Usually of a person or semi-sentient animal that can experience anger.
References ballistic missiles, whose flight paths are nearly un-alterable after a certain point.
References ballistic missiles, whose flight paths are nearly un-alterable after a certain point.
"When dad finds out I didn't submit my college applications, he'll be going ballistic!"