When someone is astounded, it means that they are amazed. We can turn that word into a more negative meaning using synonyms that mean what they find out leaves them confused. Some examples would be:
- bewilder, which means to become perplexed and confused;
- shock, when an event or experience leaves us upset or surprised;
- stagger, something makes feel astonished or deeply shocked;
- startle, the feeling of sudden shock;
- stun, a more dramatic way of saying something shocked us so much we weren't able to react for a while;
- Stupefy, my personal favourite that means something astonishes AND shocks you so much you can't think or feel properly.