catastrophizeca‧tas‧tro‧phize (also catastrophise British English) /kəˈtæstrəfaɪz/ verb [intransitive] 
to think that something terrible may happen, although this is unlikely, or think that something that has happened is much worse than it actually is: 
I have a tendency to catastrophize, so I imagined that I would die on the operating table.
to think that something terrible may happen, although this is unlikely, or think that something that has happened is much worse than it actually is: I have a tendency to catastrophize, so I imagined that I would die on the operating table.