My game has crashed :(

I wanted to load the game three times, but it crashed each times.

What I expected to happen was...:
Can someone help me, or do something for reloading the game?

What actually happened was...:
My bro downloaded the ressource pack Sphax Pure BD Craft 128x MC17-2 and then the game dont want to reload anymore

Steps to Reproduce:
1. Load the game (on an iMac)
2. Load Sphax Pure BD Craft 128x MC17-2
3. that's it