catastrophize
From Longman Dictionary of Contemporary Englishcatastrophizeca‧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.