Instalando tmux pero obteniendo "dyld: Library not loaded Referenced from: /usr/"

Intento hacer

brew install tmux

se instala, pero, probablemente debido a anteriores intentos fallidos y no completamente eliminados de instalar tanto él como libevent, cuando intento usar tmux obtengo

$ tmux
dyld: Library not loaded: /usr/local/lib/libevent-2.0.5.dylib
  Referenced from: /usr/local/bin/tmux
  Reason: image not found
Trace/BPT trap: 5

He intentado instalar libevent pero me sale:

$ brew install libevent
Warning: libevent-2.0.21 already installed, it's just not linked

así que intenté

$ brew link libevent

pero tengo

Linking /usr/local/Cellar/libevent/2.0.21... 
Warning: Could not link libevent. Unlinking...
Error: Could not symlink file: /usr/local/Cellar/libevent/2.0.21/include/event2/util.h
Target /usr/local/include/event2/util.h already exists. You may need to delete it.
To force the link and overwrite all other conflicting files, do:
  brew link --overwrite formula_name
To list all files that would be deleted:
  brew link --overwrite --dry-run formula_name

así que intenté

$ brew link --overwrite libevent

pero tengo

Linking /usr/local/Cellar/libevent/2.0.21... 
Warning: Could not link libevent. Unlinking...
Error: Permission denied - /usr/local/include/event2/util.h

así que intenté

$ sudo brew link --overwrite libevent

Contraseña:

pero tengo

Error: Cowardly refusing to `sudo brew link`
You can use brew with sudo, but only if the brew executable is owned by root.
However, this is both not recommended and completely unsupported so do so at
your own risk.

Estoy atascado.